^t^ ri^»» ^
i
NEW YORK UNIVERSITY-MEDICAL DEPARTMENT.
    INTRODUCTORY LECTURE,
             TO THE

COURSE  OF  CHEMISTRY:
            DELIVERED BT   /

     PROFESSOR DRAPER,
  RELATIONS OF ATMOSPHERIC AIR
               TO        ,..« \j •:.
     jl  ANIMALS AND PLANTS.   .  r.v *
W^    ._____^<V/S

session M»cccxi^iv-x:¥.ir../.Gni
        NEW YORK:
PRINTED FOR THE MEDICAL CLASS OF THE UNIVERSITY, BY
    JOSEIH H.JENNINGS, HI FULTON S'K^ET.

           1844-5. 
 
                                           New York,  November 4, 1844.
Prof. Draper :
  Dear Sir .— At a meeting of the Class of the University Medical College, held on
Saturday evening last, Mr.  S.  S.  Satchwell, of North Carolina, being  in the
chair, and Mr.  Edmund R.  Dabnet, of Tennessee, acting as Secretary, on  mo-
tion, it was unanimously
  Resolved—That a Committee be appointed to  solicit  for publication, a copy  of
the able and eloquent Introductory Lecture delivered this evening by Prof. Draper.
  The undersigned having been  appointed the Committee to perform this pleasing
duty, allow us to add our individual wishes to those of the Class, and to hope that
you  will not refuse so unanimous a request.
  We need not assure you how truly we  are yours, &c,
                                       Philip A. Atlett, Jlabama.
                                       William J.  Alexander, Virginia.
                                       Cyrus Arndt, Neic Jersey.
                                       John M. K. Alford, Aorta Carolina.
                                       John W. Alburt,  West Indies.
                                       W. A. Burleigh, Maine.
                                       3. Brown, .Neto Hampshire.
                                       E. T. Currie, Maryland.
                                       G. W. Clippinger,  Pennsylvania.
                                       R. H Clarke, Delaware.
                                       Oliver Crooks, Ohio.
                                       William Edwards,  Mississippi.
                                       G G. Gaither,  Kentucky.
                                       W. M. Huntingden, Vermont.
                                       B. S. James, South Carolina.
                                       John McGregor, Rhode Hand.
                                       Charlf.s T. Mount, Canada.
                                       Valentine Mott, Jr., JVeto York.
                                       Edward Perry,  Connecticut.
                                       George W. Parkhill, Florida.
                                       Wm. M. Ryer.  Illinois.
                                       J. B. Selby, Wisconsin.
                                        George M. Tutt, Georgia.
                                        T. D. Washbcrn, Massachusetts.
                                        D. E. Warren, Tennessee.
                                     New York Universitt, Nov. 7, 1844.

To Mes«rs. Atlett and others, of the Committee;
  Gentlemen —I have to acknowledge the receipt of your letter, asking for publi-
cation  in the name of the Medical Class, a copy of my Introductory Lecture.
  It would be needless for me to tell you how much pleasure it gives me to comply
with your  request,  and how deep an interest I feel in the  prosperity of each mem-
ber of the Class, who may listen to my instructions on these subjects this winter.
                           With sentiments of esteem,  believe me,
                                         Yours truly,
                                                     JNO. W. DRAPER. 
 
LECTURE.
  To assign plausible causes for natural events is the object of super-
ficial men, to find the true ones is the aim of philosophers.  Whether
it be in the infancy of society or in the infancy of an individual, a
readiness  is always manifested for giving an answer to every question
in literature, in science, in statesmanship, in theology;  and it is only
after our explanations have reached a certain degree of precision, and
their  bearings on one another are discovered, that we begin to modify
our general views, or perhaps to reject what seemed the most palpable
of our first suppositions.   It  is one of the leading characters of igno-
ranee to be full of knowledge.   In  the beginning of life there  seems
to be  nothing beyond the compass  of our intellectual apprehension,
nothing too great for ambitious exertion, but as time wears away, and
the phantoms of youthful imagination disappear, we learn to distrust
our mental powers, and  prescribe a narrow  boundary for the  things
we expect to attain.   Realities in society, and events in philosophy,
undeceive us at last;  and there steals over the evening of our days an
unwelcome conviction of-the greatness of human vanity,  and the  lit-
tleness of human knowledge.
   If these things are to be  observed  in  individual history, they  are
still more strikingly  developed  in the progress of  mankind.  When
civilization was in its infancy a clear account could be given of every
natural phenomenon,  and problems in  any department  solved and ren-
dered plain to a feeble  capacity.   But with the  progress of acquire-
ment these ancient explanations have been one by one rejected.   Only
here and  there a trace of them  remains.   Men have discovered, that
so far as  human intellect is concerned, the ways of Nature, instead of
being simple, are intricately complex. There are questions in law
clear to the client, but  doubtful to  the lawyer; doctrines in theology
plain to the zealot, but  disputed by the churches;  affairs  in politics
 for which a demagogue may rave, but from which a statesman  will
 shrink.   And so it°is in  science : in early ages men  saw that  every
 thing was plain, but now they believe that all things are obscure.
   In every science an increase of the extent of knowledge brings  also
 an increase in the boundary of surrounding  darkness.  At the most it
 is  but  a  little  way  that we see, and as no  man can  estimate the
 amount of what is unknown, neither can he estimate the full value  of
 what we  have acquired.   All the old great discoveries which have ex-
 erted so powerful an influence on our race,  have  long ago, by  reason
 of their commonness, ceased to attract our  attention ; and we are led
 to  undervalue  the  greatest facts,  because they no longer possess a
 charm of novelty.  The characteristics  of  the human  mind  are for
 ever the  same ;  whatever is unknown or  mysterious exerts over us a 
6
 powerful attraction ; whatever is newly discovered excites our curiosity
 or perhaps  our admiration ;  whatever  is old  we  neglect or pass by.
 Thus for thousands of years, in  men  of all  countries and of every
 faith,  the thunder storm excited awe,  and  the lightning  was looked
 upon as shot from the right hand of God ; but we live in a day when
 school boys bottle it  up in Leyden  phials,  and  administer  it to one
 another by  way of a joke.
   We have reached a period  in the advances of science which is des-
 tined to be fruitful in many of the most striking and marvellous discov-
 eries,—the  relations  which  subsist between living creatures and the
 inorganic world.  In this, many of those mysterious impressions which
 men  in all  ages have held,   are destined to  pass away ; and in  their
 stead there  will be replaced  those more perfect  and  more  beautiful
 views which arise from exact  knowledge.  It is the attribute of modern
 science that it gathers  around it all those poetical feelings and forma
 which arise from  whatever  is far-reaching  and  true.    There  ia
 a creative quality in the  human mind which calls into existence things
 that are new,  and fashions in novel combinations things that are  old.
 To these phantoms a duration can  be given  which far exceeds that of
 the material objects of nature, and the multitude of them which exists
 constitutes  the unreal but eternal  word of literature.   The fictitious
 events with which the genius of  Homer has surrounded  the Trojan
 siege, or the adventures of Ulysses, will last  for ever.   When, in the
 course of thousands of years, those  slow but unceasing geological
 forces which alter the  face of continents,  which dry up  rivers, which
 give inroad  to the waters of the sea,  and make new regions from its
 oozy  bed, shall have  utterly removed  all traces of objects  which in
 former days the landscape revealed, still, in the imagination of the
 scholar, Scamander will roll his waters, and the laughter  and  revelling
 of the Suitors will still  re-echo in Ithaca.  And if these are the results
 of the  human mind operating on objects that  are  in  themselves insig-
 nificant,  what are we not to expect when the  subject of its contempla-
 tion has risen into an awful magnificence, and stands in relation to the
 world of life and death,  the course of animated forms,  and their con-
 nexion with  inorganic things.
  During the past summer, in preparing  for the press a work which
 I have recently published on  the Chemistry  of Plants,  my  thoughts
 have  been forcibly turned to these things.  The  inorganic and  the
organic world are blended together, depending both of them on common
 laws.  From the atmospheric air which is around  us the vegetable
world comes into existence, under the influence of that arch  magician
the Sun, and on the resulting organized forms  animals find their proper
food.   The  operations of that  distant star, therefore, furnish food for
man—food of which his living structures are formed  ; and these, during
the course of life, and by the  act of death, are broken down, and their
constituent parts are restored to the air again.
  If thus the vegetable world  springs from inorganic gases in the air
by the light  of  the sun,  and  is destined to afford  nourishment for  the
various tribes of animals,—what, then,  are they  ?   The processes of
destruction which are constantly going forward in the animal frame—
the constant  carrying away by respiratory and  other functions, which 
7
are in  action night  and day—the constant introduction of new matter
in the form of food  ;—there is no motion that I execute—this finger is
not lifted—this voice does not make itself heard, without the destruc:
tion of a  given weight of organized  material,  a destruction which is
essential  to the production of a given amount of  force.  In a steam
engine, by which a given quantity of work is to  be done, a given
weight of coal must be burnt.  It is in the transmutation of particles
from one condition to another that physical forces  arise; and  all the
movements that I 'execute, all the powers that  I exert, originate in the
passing of particles from the organic to the inorganic state.
   Do  not, therefore, these things invest the commonest phenomena  we
witness with superabundant interest ?  The act of  breathing ceases to
be the escape of noxious gases from the lungs.   The particles of which
those gases  are composed,  are passing from the living  state into  the
condition  of death,  and this atmosphere  which is  around us, presents
itself as made up of crowds of atomic forms which  have  been expend-
ed in the  production of every kind  of movement and change.  In  the
few years that have elapsed since I came into  the  world,  I  have
thrown into  that atmosphere more than sixteen tons weight of matter
which has  circled in these veins;  and  I am  only one  of myriads of
living things.
   As  thus  these particles  are removed from  animated systems, and
dying escape away into the atmosphere,  they shall leave behind them
marks of the offices they have performed.  Their  migration from  the
living to the dead state has been for the production of force—force
which has been expended in procuring for me all that might subserve
to animal pleasures or gratify intellectual desires.  This enormous
destruction  of material has  left its impression behind,—impressions
that are  not perishable in their  nature,  but last till the close of life.
Whatever,  therefore,  I have learned from the experience of years, or
from the  education of youth,  whatever I have gained by exertion, or
lost in the course of events, has left a permanent impression,  and  it is
 in these things that individual character arises.   Though there is  a
 daily  change  of organized  structure, the consciousness of personal
 identity remains.
    Whilst, then, this  body has ceased to be composed of the same iden-
 tical parts which entered  into its  constitution  a year  ago,—for those
 have passed away  into the atmosphere, and new ones have taken their
 places, and  processes of destruction and  renovation have been accom-
 plished ; these unceasing changes have left no impression  on, and done no
 injury to the intellectual principle within.  In an instant, and spon-
 taneously, there come to recollection words  which I  have  heard in
 early life, which have been  registered on the  tablets of the brain,  and
 in dreams  at night as well  as during the business of  the day, there
 arise before me long forgotten forms of scenery that  I once beheld,
 the remembrance of transactions in  which I have borne a part.   Do
 not then  these noble discoveries of modern Chemistry impress on a re-
 flecting mind a deep  and absorbing lesson ?   If,  in the  midst  of all
 this mutation and change, this hourly escape of dead atoms  by respi-
 ration and  other processes, this constant  re-introduction  of new matter
 in the form of food, and its  transient continuance  as a  part of a living 
8
mechanism, there s<ill remains behind an intelligent  principle with all
its affections and  feelings,  and acquisitions and knowledge unaltered
apd untouched,—do not these things declare plainly, that after the act
of death shall  have utterly broken down and dispersed and dissevered
the parls of this organized  frame, there  still  shall remain that same
intellectual principle unscathed,—still bearing the impression of what-
ever it has seen, whatever it has done, whatever it has endured !
  It is the quality  of  knowledge  in  expanding our  views to give  us
new conceptions of things which  are around.    To  those of you who
are commencing the study of  medicine, who hear for the first time to-
night  the ideas I am endeavoring  to unfold, ideas  which the recent ad-
vances of Organic Chemistry have taught us, what new associations
at once spring up.  You leave this room not with mere words  jingling
in your ears, but the possessors of a new, a great fact.   This atmos-
phere, the air which  envelops us on all  sides, is  no longer an inert
uninteresting mass through which winds sweep, but  it comes  forward
at once into its true position as the connecting link between vegetable
and animal life.   As I have said, organized by the  rays of the  sun,
from it are condensed the various  vegetable forms which adorn the face
of the earth and furnish food" for all animal races, and to it  there re-
turn unceasingly during life, and totally after death, those animal forms.
It is the grand  receptacle from which all  living things spring, and to
which they all return.    It is the  cradle of vegetable and the coffin of
animal life.  Look also at the sun : evjen the magnificent views of the
astronomer are  here surpassed, and that gigantic star no longer appears
as a centre or focus of mere mechanical force,  who draws up comets
from the abysses of space and with an inexpressible velocity precipi-
tates them  headlong back again ; who afar off watches the  revolving
planet glide on its elliptic  path,  or  makes the tides ebb and flow  in
the seas ; but he appears as the fountain of light and of life, who spreads
in the torrid zone  a luxuriant vegetation, and in  autumn  ripens the
harvests for our use ; whose many colored rays during  the  revolving
seasons are occupied in  fashioning and forming  food for us, or evapo-
rating pure water from the sea, or condensing clouds  in the sky, which
give an air of change  and life in those regions of eternal repose.
  Philosophers have long ago determined, that  light consists of vibrato-
ry, undulatory, or  wave-like movements which take place in an ethe-
real medium existing every where.   It is  a more recent discovery that
these  vibrations are the  first origin of the vegetable world.    In the
work  to which I  have alluded, I have given  the details of this most
interesting  connexion.   Out of a limited   number  of ponderable sub
stances such as carbon, nitrogen,  hydrogen, oxygen, and a few others
all kinds of organized structures are formed, and there is an extensive
machinery to collate and group together these different bodies    Light
in itself can produce as  many different  effects as there are possible
combinations of color, for each one of its rays has peculiar powers  of
its own and ,t is  also  attended  by  other invisible and imponderable
principles which have their modes of action.   An organized structure
of a given kind is therefore the result  of the  operation of many of
these  forces, and is an expression  of the aggregate action.   In the full
development of a  perfect tree there has  been expended a  measured 
9
quantity of forces of light or of heat, and  the  organized  mass as it
stands before us is the product of those forces, is the resultant of mil-
lions of vibrations of the luminiferous  ether, which have  acted upon
ponderable atoms ;  vibrations, which  have stood in a certain relation
to each other, as the  symmetry of the  vegetable parts  indicates.  In
the operations of human  agency something of the  same though  of a
grosser kind  may be seen.   We have not it is true, the power  of cal-
ling into existence,  or of determining in an enduring shape, or of giv-
ing an embodied form to material atoms; hut in  the same manner that
nature, operating through ethereal undulations, creates the various forms
of vegetable life, there has been committed  to us a control over those
grosser undulations which move in atmospheric air, and constitute sound.
Tho  imagination, the genius of the great  masters  of music, have al-
ready grouped  together combinations of these waves  which are des-
tined to an earthly immortality ; combinations, which, when once heard
leave their indelible  impression on the memory, and are to us an embodi-
ment of symmetry and harmony.   These  ideal creations which exist
only  for the mind are analogous in very many points of view to those
more tangible creations which are formed by ethereal waves and which
nature has reserved in her own hands.  The symmetrical or beautiful
forms which are transmitted to the brain by  the  eye, appeal at  last to
that same, that common principle which  receives melodious or harmo-
nious sounds transmitted by the ear, and the creations of human genius,
whether they  be expressed in the language of music or  painting, whe-
ther they are heard in the Cathedral or seen on the  canvass of Claude
Lorrain, give us pleasure, because their final impression is made on a
mathematical organ, which is so constructed as to appreciate whatever
is symmetrical in position, whatever is graceful  in figure, whatever is
harmonious in movement.
   From this point of view, therefore,  I look upon the vegetable world
as  an embodiment of the action  of ethereal agents.   A  tree, when
covered with  blossoms in the spring, or laden with fruit  in the autumn,
is a resultant  of the play of  those active forces which have been emit-
ted by the sun;  an  expression  of  what has been  done by vibratory
movements operating on ponderable molecules.   As soon as the young
plant  has exposed itself to the  solar beam,  growth rapidly begins to
take  place, and organized matter to be  condensed  from  the air, and
now a green color is  developed,  and the stem elongates  and leaves are
put forth.   In carrying forward all those multiplied operations which
have ended in these events, its leaves and its stem have gone upward in
search of light.—light which has symmetrically arranged their  parts
and  furnished their substance.   But these general  views are far from
giving us  an  accurate  idea  of  the forces that have been expended or
the motions which have been executed in producing the result we con-
template.  'A forest tree, from its magnitude, rising perhaps a hundred
feet from  the ground, and spreading its branches over  hundreds of
square yards, may  impress us with a sense  of sublimity; a section of
its stem ndidit assure us that it had lived f>r a thousand years, and its
total  weight could only be expressed by  tons.  \n object like this may
indeed cal!  forth  our admiraiion, but  that admiration is expanded into
astonishment,  when we come to consider minutely  the circumstances 
10
which have been involved in producing the result.   If we conceive a
single second of time, the beat of a pendulum, divided  into a million
of equal parts,  and each one of those inconceivably brief periods  divi-
de 1 again into a million of other equal parts—a  wave of yellow  light
during one of these last small intervals has vibrated five hundred and
thirty-five times.   And now that yellow  light is the agent which has
been mainly involved in building up the  parts of the tree, in fabrica-
ting its various  structures, and during every one of a thousand sum-
mers, from sunrise to  sunset  the busy rays have  been carrying  on
their operation,—who then can conceive when in the billionth of a second
such enormous  numbers of movements are  accomplished, how many
have been spent in erecting an aged forest oak ?   Who also can con-
ceive the total amount  of force employed from  century to century in
arranging the vegetation of the surface of the globe ?
   I therefore  regard a planetary body like the  Earth, in  its orbitual
revolution round the sun, as a predetermined focal centre on which the
emanations of that star shall be expended, first in producing vegetable
organization,  and  finally in lending their aid to the evolution of ani-
mal intellect.   The forces which Newton revealed, as  urging such a
body forward, or causing it to  glide in its elliptic path, appear only  as
an incidental  though essential part of the  mechanism of the Universe,
the interest of which disappears in that higher interest which must  at-
tach to whatever stands in intimate connexion with  organization and
vitality.   Those  many-colored luminous wavelets  which  are cease-
lessly crossing  the  interplanetary spaces, go forward on an appointed
errand and sooner or later discharge their final task ;  nor are the pla-
nets in the solar system a colony  of opaque globes rotating without
purpose or end  around the central attractive mass.   The solar system
is  an orb of movement and light, full of vibrations of every tint visible
and invisible, which here and there envelops and enshrouds revolving
points of organization and life.
   Whatever, therefore, we see around us in the  world of organization
has originally  come from the  atmosphere, and to the atmosphere it ia
hastening to return.  What, then, is this  reservoir from which so many
wonderful things spring ?   The earth is about 8000 miles  in diameter,
the atmosphere  is about fifty miles deep,—to the mass of the globe,
therefore, as astronomers justly say, it bears about the same proportion
that  the  down  which covers the surface of a  peach, bears to the peach
itself.   What!  and is it this  mere film that  is the seat of organization
and life?   Is this the narrow boundary that  comprizes  the domain of
living things?  When  I told you a while ago that already I alone had
thrown  into the air several tons of disorganized  matter,  the  assertion
seemed difficult enough to believe, but measured in the balance in which
I am now weighing the world, what  am  1 and you and all other living
things?   If, on this insignificant  film, in the course of ages,  vve can
make no appreciable impression, who shall put a  proper estimate on  all
the power that  we can exert, on all the most alluring objects of human
life?   Is there  not an absolute nonentity  of force, an absolute insignifi-
cance in all those projects which occupy the period of our existence ?
Are not the  spaces of life long enough for all those  trifling purposes?
We dance like  motes in the air, now in  the sunbeam of pleasure and 
11
now in the shades of affliction, and a little while suffices  to sweep ua
and our works, and all our hopes and  all our cares, into an absolute
and irreversible oblivion !

              '* The boast of heraldry, the pomp of power,
               And all that beauty, all that wealth ere gave,
               Await alike the inevitable hour:
               The paths of glory lead but—to the grave.''

   As we shall prove abundantly during the winter, the solid substancea
whicli are found in plants are derived from the Carbonic acid of the air,
by the decomposing  agency of the Sun.   And it is on this  material
alone that the various tribes of animals subsist.   We can therefore see
that the vegetable world occupies a  most important and intermediate
position between the highest animals and  inorganic matter.   By the ac-
tion of light the decomposition of Carbonic acid gas is effected, and from
a gaseous substance trees and vegetables spring,—the various parts of
which are absolutely essential  to the  support of animal life  in the way
of food.   Plants, therefore, in the aggregate, may be regarded as solidi-
fied gases, which have been brought into that condition by the solar influ-
ence.   They constitute, as the French chemists justly say, an enormous
reducing  machine in  constant activity.   How is it then with animals ?
   It is t lie office of animal life to discharge precisely the opposite duty
to that of plants.   The  food which they take and  which has thus been
provided for them  by the  Sun,  enters into their  systems for a time, and
becomes  a transient part  of their structure.   But  oxygen gas, con-
stantly introduced  by the lungs, effects the combustion of this solid ma-
terial, changes its hydrogen into water,  its Carbon  into Carbonic acid,
and it is thrown once more out into the air in the exact condition in which
it  was before the leaves of  plants commenced their operation on it.
   Thus, therefore, you see that if, in a chemical  point  of view, the
vegetable world is  a  great machine of reduction, the animal  world is
correspondingly a  machine of combustion ; the one is antagonistic to
the other; the one  also  is essential to  the existence of the other.   From
the air plants constantly withdraw carbonaceous matter, to the air ani-
mals  constantly restore the same.  And  now we have good reason to
know, that for a thousand years the composition  of the air has remained
unaltered, whilst these incessant abstractions and additions have been ta-
king place.  And we perceive that these apparently unconnected chemi-
cal doctrines bring us at last to the extraordinary conclusion, that the
amount of vegetable and animal life  are by the Creator rigorously ad-
justed  to one another;  that plants do not take more from the  air than
animals restore, but that the action of the one is so adjusted to the ac-
tion of the other that during the lapse of a thousand  years  the atmos-
phere remains untouched as respects its final constitution.
   Let us carrv our thoughts back to  former epochs, and see what then
took place.   What is it that geology reveals, and which we all  know
to  be true ?  In  many parts of the globe, and in  none more abundantly
than the United States, enormous quantities of carbonaceous matter oc-
cur; deposits that cover hundreds of square miles  in surface, and are
of unknown depth,  constituting the great  fields of Anthracite and  bitu- 
12
 minous coal.  The aggregate of this in Europe, Asia, Africa, and in
 the great islands, cannot be estimated at less than many thousand mil-
Jions of tons, yet, as is well  known  for no fact  is  better established
 in science, the whole of this is the remains of vegetable growth.   The
 ways of Nature are unchangeable.  Invents as they happm now, hap-
 pened also a thousand  years ago.  And just as the sunlight with  us
 forms the solid  materials of which vegetable structures are compo-ed,
 so did it form the solid matter of which  that coal  is  made.  The Car-
 bon  which is thus stored up in the Earth existed formerly as Carbonic
 acid in the air, from which it was carried away by primeval plants and
 in the course of events buried in the  ancient strata.  The  warmth
 therefore, which on a winter's evening we derive from  the combustion
 of coal, and the light which is emitted by the flickering flame as it plays
 over the surface of the fire, originally  came from  the Sun, and were
 absorbed by the vegetable leaves, and now  are restored once more  by
 the process of combustion ; and  after its long imprisonmr nt the Carbon
 escapes  back  again  into the  atmosphere from which  it originally
 came.
   The French chemists are therefore right in their assertion that though
 within the periods of history no change has  happened to the constitu-
 tion of the earth's atmosphere, if we go back sufficiently far, the reverse
 appears, and that the primeval atmosphere which once surrounded the
 Earth is now divided into three  distinct  and well marked regions,—the
 present air—the  great coal deposits of  all kinds—and the bodies  of
 all  vegetable and  animal forms.   That  this tri-partition has  been
 mainly brought about by the Sun, who  whilst he has been occupied in
 directing the revolutions of his attendant  planets,  has also arranged
 and beautified the surface of the Earth, and prepared it for the recep-
 tion of intellectual races.
   What, then, are the final impressions we gather from these conside-
 rations ?   For  as we advance in knowledge all our views of the na-
 ture and connexions of things change, and new and inter sting  relat'ons
 spring up.  Whoever  among you for the first  time  hears  of these
 results of modern science, must necessarily have his former ideas en-
 larged,  and  his  understanding  of  the qualities and  connexions  of 'he
 most  obvious things  around  him  improved.   In  the midst  of  t'  se
 changes, moreover, new thoughts must  necessarily  suggest themse'vog
 —thoughts which tend  to the  nature and laws of the iw < rnm< nt of  he
 world.  The great divisions of the animal and vegetable kingdoms c  me
 now before us, not as solitary and independent existences, but as tl i   <-s
 made for  one  another and  acting upon one another.   There are.  >~.
 sides, nobler and still more interesting reflections.   It  is a prop- rt,- of
 all the works of man, that they continue to produce ihei>  int'-nde1  <-P.
 suit  for a time,  and then they pass away,—the temple, goes  <'o>< ■•  in
 ruins, the ship is lost in the sea, and strains of music die  away in  'he
 air.   Of the words and  the  works of  the great men  who lave re' ed
 themselves to the head of their race, what in a rew  years k the i'   -i-
 table destiny ?   Is it not to come to an  end ?  Of the  tw. n'v mi'   ns
 of people who  inhabit  this country, how inanv are  t':ere who '  <ve
 never heard of the battle of Plmrsalia  ? how manv are iIk re w!   lo
 not know what took place in the pass  of  Thermopylae 9   It  is, I <■  y, 
13
the property of all  human works sooner or later to come to an end.
But how is it in natural affairs ?   The  facts of which we  have  been
speaking serve to show that every thing is arranged  as it  were  in a
recurring series—a series which turns in upon  itself; and  from one
point to another there is a perpetual tendency  to  restore  all things  to
their original state.  The substances of which vegetables  are com-
posed,  and which they abstracted from  the  air,  they yield as food  to
animals, who, when they have done with it,  restore it to the air again:
it  runs, therefore, in an  eternal cycle—the inorganic, the vegetable,
the animal—the inorganic, the vegetable, the  animal—and so it goes
on for  ever.   It is the peculiarity of  the works of God that they con-
tain within themselves principles of self conservation,  the power  of
evolving from apparent ruin  the principles of order.  The affairs  of
men march forward in a straight line, and each moment  removes them
farther and farther from the original point:  the affairs of nature return
in circular paths, and after the lapse  of a time are all  brought back to
the point of departure, and commence once more their perpetual motion.
The stars in the sky are examples of these truths.   They revolve  in
their elliptic orbits  age after age, and punctually come back to the
starting point.   We see the moon waxes and wanes, and runs through
her monthly race :  the first man saw  the same thing.
   Whilst thus in human affairs the element of ruin  is necessarily in-
volved, in the affairs of nature the element of eternal duration is con-
stantly bound  up.   Each class  of events  contains  within itself the
principles of its future recurrence, and the march of things is  so regu-
lated as to give birth to similar things hereafter.  And may we not
gather from these philosophical facts  impressive lessons ; and, compa-
ring small things with great, discover from  the phenomena of  the gov-
ernment of the universe,  the  true principles for the government of
man?   Whatever  is meant  for duration must contain within itself the
spontaneous  principle of change—must include  as it were in its very
nature the law under which its mutations can be accomplished.  These
are the same results to which, by following  another route, the  progress
of civilization  has brought us.  All constitutions which, like the laws
of the  Medes and the Persians, never change, must, like the laws of
the Medes and Persians, under the necessities of nature, rapidly pass
away.  But forms of government which are to last  for ever,  must in-
clude  within themselves the well marked laws by which they them-
selves  can be changed ; an apparent  paradox,  but yet a philosophical
truth.   What does  the history of our race tell  us?  Whenever the
attempt has  been made to cause things to remain in a  fixed  position,
the pent-up forces have gathered strength, and every barrier has been
burst through by a  final  explosion;  but wherever the ways of nature
have been unwittingly followed, and the affairs and government of so-
ciety have been allowed to change with the  changes in the condition of
society, stability, endurance  has been the result.
   In these circuitous channels, therefore, all  natural events flow, and
each  isolated fact  is the  daughter of things which are older,  and the
mother of things  that  are younger.   In  the Universe no event has
ever happened by  and for itself alone ; there  were  concurring and
preceding events which gave it birth, and it joins with other contempo- 
14
  raneous events to determine the future.  In the necklace of time there
  is a thread of destiny on which  the  beads are strung,  which  forces
  each to keep its proper position.   Affairs come forward in their due
  rotation, they produce their predetermined  effect, they are  over; and
  whether it be in the revolutions which take place on the  surface of the
  earth, or in the revolutions that take place in the celestial bodies above,
  the endless law of action is observed with inexorable precision.   Those
  fortuitous  events which occupy  so large  a space in the estimate of
  men, the free actions of the human race or the voluntary determina-
  tion of animals, take place on too insignificant a scale to touch the far
  reaching result.    We dance  in  a mazy path, perhaps often without
  reason or rule, but we are only microscopic forms  that occupy an al-
  most invisible space.  Do the motes that dance in the sunbeam  inter-
  fere  with the onward sweep of the ray ?
   These considerations,  moreover, serve to enlarge  and purify  our
 views.  They point out to us the connexion which subsists between
 ourselves and the  world in which  we live, a connexion  as it  were of
 brotherhood with all animated things.   Repudiating every misanthro-
 pic feeling, they point  us to a common origin and a common destiny;
 they  call on us to rejoice in the happiness  of him  who is successful,
 and to be merciful to him who is in distress.   They bid us look on the
 surface of the globe, and  remember that there is  no spot upon  it in
 which the ashes of those who have  lived are not entombed.   Is  there
 a breath  in the air, is  there a wave in  the sea,  which  has not flowed
 over the dead ?   In the quietness of the night and in the tumult of the
 day  there is no moment in which myriads of living  forms do not come
 to an end.   And of the myriads even of our own race who have  in-
 habited the  earth, what  is the  record  that remains  ?   It is  here and
 there that some gigantic  mind or some energetic spirit, has refused to
 go back into the land of the forgotten, and has  burst through the law
 of destiny,—physicians,  philosophers, statesmen, and soldiers, appear
 among the ruins of the past.    Give me the man who trembles to die.
 The name of Hippocrates, the father of us all, stands forth imperisha-
 ble in pre-eminence.   There is something more  than an empty vanity
 in earthly immortality.   To speak to posterity, and  after the lapse
 of a thousand years to make  the  hearts of future   men  leap at the
 words you  have  uttered or the deeds 'you  have done.   That is  not
 Death.
   From  the revolutions which thus  happen  to  all  things, this move-
 ment  from state to state, this transmigration of bodies, we  may gather
 a lesson which of all other lessons is most useful to young  Physicians.
 As I have already said, the glowing expectations of  youth are cramp-
 ed into a narrower space by mature life, and end in  disappointment
 with the experience of  age.   And indeed there are  few who, even in
 the morning of life, escape the bitterness of this  lot.   Amono- those of
 you whoat  the close of this session are to go forth  and enter on the
 race of life, how many are there whose  fate is already written, and
those  promises that hope  has  held out  are  predestined not to be ful-
filled.   From the  thoughts which  have occurred to  us this  evening
we may gather that the affairs of life are never continuous, that there are
seasons of prosperity as well  as  seasons of disaster,—that there is no 
15
evil so great but that it will come to an end,—that in the inorganic, in
the living, and in the  moral world, there is a  succession of change.
Remember, it is  in the darkest thundercloud  that the most brilliant
lightning  sleeps.   And, perhaps, away in the far  West,  and in some
future year, some of you will remember the things I have been telling
you to-night,—-that grains of dust and drops of water pass from change
to change and take on in succession  many a different form.   It  may
then recur to you in your hour of disappointment  that you were once
told, that the tear which has  flowed  even in  the  anguish of despair,
must sooner or later re-appear in the rainbow—which is the emblem
of hope.
   It has always seemed to me one of the most enchanting results of
chemical problems and chemical pursuits, that when you thus  follow
them out they uniformly  bring  you to things which relate to yours-lf
 at last.   There is no  department of human knowledge which has done
 so much for the human race, or to which the rapid  advance of civili-
 zation is so much due, as to this particular science.  You saw this
 evening where we commenced, you see to what we are led.  It is that
 practicability that is in it, that near relation which it holds to us and
 our doings, which spreads over it such a charm.  You can easily un-
 derstand how it is that escaping  from the underground recesses of the
 caves of alchemists,  it now forms the  right arm of power of some of
 the greatest nations.   What is it that constitutes the wealth of England,
 that controls her coal, her iron, that manufactures  her cotton?  Why
 is it that this science  is looked upon almost with veneration in France ?
 You can understand how it is that some of the greatest monarchs now
 living amuse their leisure hours with these pursuits.  But, dismissing
 these" generalities, your estimate of its importance will be permanently
 fixed when you shall find how closely it stands in relation to your own
 pursuits.  It is  for this reason that I  propose this winter to make these
  matters  a formal portion of our study, and have prepared a book which
  contains the evidence of what I shall have to offer you on the Chemis-
  try of Plants.  So far as I  know in no College in the United States are
  the   modern discoveries in  Animal  Chemistry introduced,—the very
  things which relate  to the physician.   It seems to be the  opinion o
  most teachers of Chemistry, that inasmuch as this  particular depart-
  ment wants the alluring brilliancy of experiment, and addresses  itself
  rather to the intellect than the eye, that students of medicine in general
  were indisposed to undergo the trouble  of mastering its dry formulas.
  Last winter, as many of you know, I made a slight trial of the matter,
  —the seats that it was predicted  would be empty, were fuller  than be-
  fore.   The American student was neither more  lazy, more ignorant,
  nor more slow to perceive the great fact, than have been the students
  in Germany!   The  time had come.  And  now I hope to see this Uni-
  versity, as it is the first  to introduce  these capital improvements, keep
  the first in the emulous race with all its sister institutions.   Iwan
  see it the  ereat factory of Chemical discoveries and Chemical doctrines
   nthIwe'sfern'world.  I ™tto^thedootrii«rfChemi^o.n^
  and  experiments in Chemistry made, and above all and ^"ff^f
  to the thing, Chemical  theses written.   It  is in this spirit that I enter
  on my work this winter j and if, as I hope, the same  spirit may arise in 
16
you, though it is little that the professor, it is much that the student can
do.  There is nothing which would yield to me more heartfelt gratifica-
tion, than to  see those to whom I had taught the rudiments of this sci-
ence take their rank as original discoverers with those great European
chemical physicians who are fast forming Organic  Chemistry into the
shape of a perfect science.   And if the  opinions  which I have taught
and the views I have published, should, by the discoveries of my own
pupils,  be  found irreconcilable  with advancing knowledge,  I  trust I
should feel, as the greatest  of modern historians has  said on another
topic, a little of  that spirit which  animated those English sailors who
were confined prisoners in the hold of a French frigate during the bat-
tle in Algesiras bay, who, regardless of threats of instant death  from
the officers around,  and of  the  imminent danger of being sent to the
bottom by the friendly discharges,  gave  three cheers  for every broad-
side  as it  was poured in, because  they  knew  that it came  from  the
hands of their comrades  and friends.
                       JUST PUBLISHED,

         CHEMISTRY  OF  PLANTS,

A. Treatise on the Forces which produce the Organization of Plants—with  an Ap-
pendix, containing Feveral Memoirs on Electricity,  Capillary Attraction,  and the
Chemical Agency of Li^lit.  By John VY. Draper, M. D., Professor of Chemistry
in the University of New York.  In one large quarto volume, on fine paper, and
large type, with numerous Engravings on steel—one of them colored.  Price 02.50.