[Reprinted from the Boston Medical and Surgical Journal of 
January 19,1887.1 / 
OXALURIA. 
BY F. W ELLIS, M.D., OF SPRINGFIELD, MASS. 
By oxaluria we mean the presence of oxalate of 
lime in the urine. It is not a disease - it is, at most, 
only an expression or symptom of disease. It is 
doubtful if we are justified in considering the presence 
of a slight amount of calcic oxalate in the urine as ab- 
normal. Traces of its presence in urinary sediments 
from individuals in apparently excellent health are 
very frequently met with. In some instances, the 
oxalic acid may be ingested in the vegetable food 
taken, for oxalic acid and the oxalates are found in 
very many plants. It is not likely, however, that 
these cases of slight oxaluria are always due to this 
cause. Every practitioner who has occasion to make 
frequent microscopical examination of the urine must 
be impressed with the number and variety of the cases 
in which calcic oxalate is encountered in this secretion. 
This frequency of occurrence tends to make us under- 
estimate the importance of the subject. When we 
reflect upon the importance of the chapter in medicine 
nd surgery devoted to urinary calculi, and when we 
ecall the fact that one of the most frequent, and cer- 
tainly the most dreaded, constituent of the calculi is 
calcic oxalate, nothing further is needed to indicate 
the interest that every physician should take in the 
subject of oxaluria. The calcic oxalate, or mulberry 
calculus, is harder than the other varieties, and, conse- 
quently, is the most difficult to crush and remove by 2 
litholapaxy. It is apt to be rough, and, as a result of 
this irregularity of surface, excite a great amount of 
irritation. Even when it does not form the main sub- 
stance of the concretion, it often serves as the nucleus 
and starting point of others. For these reasons, every 
fact that tends to enlarge our knowledge of the mode 
of origin of calcic oxalate in the economy, and the 
causes of its deposition in the urinary tract, must be a 
desirable addition to medical science. Regarding the 
subject from this standpoint, no practitioner can ques- 
tion its importance. 
There is, however, great diversity of opinion as to 
the diagnostic significance of calcic oxalate deposits in 
the urine. Since the first recognition of this sub- 
stance as a urinary constituent, numerous contradic- 
tory statements have been made regarding the signifi- 
cance of such an occurrence. After an attentive 
perusal of the literature of the subject, and a careful 
consideration of the various theories advocated to ex- 
plain the origin of the oxalic acid, one cannot escape 
the impression that something essential to the success- 
ful elucidation of the question has been overlooked, 
or has not yet claimed sufficient attention. 
One of the mistakes generally made is that of re- 
garding oxaluria as a disease, and not as a symptom. 
Oxaluria, like albuminuria, is a symptom. The causes 
of albuminuria are widely different in their character, 
and the same may be true of oxaluria. Hence, in 
seeking for an explanation for the appearance of oxa- 
late of lime in the urine, we have no right to expect a 
single one applicable to every case. 
In treatingof oxaluria and oxalmmia, it will be useful, 
at the outset, to consider some of the undisputed facts 
bearing upon the subject. First, we know that oxalic 
acid is a poison. Fatal cases of poisoning with this 
substance are not uncommon. The careful experi- 3 
ments of Koch1 demonstrate that the soluble oxalates 
paralyze the muscles, heart, and nervous system. A 
solution of neutral oxalate of ammonium injected be- 
neath the skin of a frog caused fibrillary muscular 
contractions, and paralysis of the voluntary muscles 
and the heart. The lethal dose, for the frog, was 
found to be 12£ m lligrams of the salt. Experiments 
upon warm-blooded animals gave quite similar results 
when the drug was injected subcutaneously. 
Another well-ascertained point is, that a certain pro- 
portion of the oxalic acid or oxalates introduced into 
the body through the stomach or subcutaneously reap- 
pears in the urine under the form of calcic oxalate. 
In the experiments of Koch just mentioned, crystals 
of oxalate of lime were constantly found in the kidney, 
and in that organ alone. In cases of poisoning by the 
acid, a large amount of calcic oxalate crystals can be 
obtained from the urine. 
These two facts having been determined ; namely, 
that oxalic acid is a poison, and that it manifests its 
presence in the system by its elimination in the urine 
as calcic oxalate, are we justified in assuming from 
these premises that whoever voids oxalate of lime in 
the urine is being poisoned? The views of different 
writers upon this point are very discordant. No un- 
equivocal answer can be given to the question until 
investigations have been made to determine the effects 
following the long-continued administration to animals 
of small doses of oxalic acid and the oxalates. I am 
not aware of any such experiments having been made. 
Another subject for experimental investigation is the 
action of solutions of calcic oxalate upon the physio- 
logical processes. I think that we have very little 
reason to expect, a priori, that solutions of calcic 
1 Wirkung der Oxalate. Archiv. f. exp. Path, und Phar., Bd. 14, 
s. 153. 4 
oxalate ■should not possess toxic properties. Ringer 2 
has endeavored to show that the soluble oxalates 
arrest function by the withdrawal of lime from the 
tissues. He asserts that a lime salt must be present 
in the circulating fluid, to sustain the contractility of 
the cardiac muscle. He reports the following striking 
experiment: The detached ventricle of a frog's heart 
was enclosed in a Roy's " tonometer," and was sup- 
plied with an artificial blood mixture through a perfu- 
sion canula. A small amount of a five per cent solu- 
tion of oxalate of ammonium was then added to the 
circulating mixture. The ventricular contractions 
immediately grew weaker, and contractility ceased in 
a few minutes. The nutrient fluid was then diluted, 
but the ventricle remained inactive. A small amount 
of a one per cent solution of calcium chloride caused 
a speedy return of the spontaneous contractions. 
Ringer reports another interesting experiment 
which will chiefly interest us : He prepared two solu- 
tions, one containing chloride of calcium, and the 
other oxalate of ammonium. The proportionate amount 
of these ingredients were such that equal quantities of 
the two solutions nearly neutralized each other, a 
slight excess of the lime salt remaining. Of course, 
the combination of these substances produces oxalate 
of lime. It was found that when quantities of the 
two solutions sufficient to just neutralize each other 
were added to the fluid supplied to a frog's ventricle, 
the cardiac contractions became weakened. A suffi- 
cient amount of the oxalate of lime must have been 
dissolved by the circulating fluid to poison the cardiac 
muscle. Hence Ringer admits that oxalic acid exerts 
a direct poisonous action upon the muscle, and what 
he asserts of oxalic acid, in the light of this experiment, 
would seem to be true of calcic oxalate. Although 
s Practitioner, Vol. 34, p. 81. 5 
these experiments need confirmation, and require 
to be supplemented by a variety of others performed 
upon warm-blooded, as well as cold-blooded animals, 
it does not appear that we have any theoretical reasons 
for doubting that considerable amounts of oxalate of 
lime circulating in the blood must have a deleterious 
action upon the functions of the body. It is true, the 
urine of persons in apparently good health may some- 
times contain a relatively large amount of calcic oxa- 
late sediment. 
Roberts 3 states that " subjects of mulberry calcu- 
lus, especially children, are often in the enjoyment of 
blooming health." As an offset to this assertion, 
however, we have the authority of Ultzmann 4 that 
weakly and anaamic children are the ones that are 
particularly predisposed to oxalate of lime calculus. 
Chambers5 asserts that under-fed children living in 
the country often have oxalate of lime in the urine. 
According to my own experience, a copious sediment 
of oxalate of lime is not often found for a considerable 
period in the urine of persons in vigorous health. Its 
long-continued presence in this secretion is generally 
indicative that some of the functions of the individual 
are not being performed as they ought. 
The oxalate is very insoluble in water. This prop- 
erty tends to render obscure the explanation of its 
mode of elimination from the system. The acid phos- 
phate of sodium, which is ordinarily present in fresh, 
normal urine, has been found to have a solvent action 
upon the calcic oxalate. This would explain why the 
oxalate is held in solution in fresh urine, and its grad- 
ual deposition, as the acid phosphate becomes con- 
verted into the neutral phosphate, in consequence of 
chemical changes taking place in the urine. This ex- 
3 Urinary and Renal Diseases, fourth edition, p. 103. 
4 Die Harnconcremente. 
3 Manual of Diet, p. 271. 6 
planation, however, does not account for the solution 
of the oxalate in the blood, from which the urine is 
secreted. It has been found that some other saline 
solutions have a slight solvent action on the oxalate. 
The oxalate, moreover, is not perfectly insoluble in 
water. Storer6 gives the solubility of calcic oxalate 
in water as 1-500000. It has been estimated that ten 
ounces of water are capable of dissolving 1,000,000 
of the crystals. That the oxalate can be dissolved in 
the stomach, is proven by the fact that it reappears in 
the urine after the ingestion of foods containing it. 
There can be no doubt therefore, that the substance 
can be dissolved, or held in solution in the alimentary 
tract, blood and the urine ; but the laws regulating its 
solution and deposition have yet to be discovered. 
Why it should be deposited in the kidney or bladder 
of one patient, and another, whose urine is loaded 
with it, should escape, demands further investigation 
to determine. And, of the many unsolved problems 
connected with the subject of oxaluria, this is perhaps 
the most important. When the laws governing its 
solution and precipitation within the body are made 
manifest, we may reasonably hope to be able to pre- 
vent the formation of calculi composed of it in oxa- 
luric patients. There seems to be no doubt that mucus 
favors the crystallization of calcic oxalate; acting in 
this respect, very likely, like a foreign body. The 
crystals are generally found in the urine intimately 
mixed with the cloud of mucus that slowly falls to 
the bottom of the receptacle. The starting-point of 
many calculi is probably formed by a clump of mucus 
that has occasioned the crystallization of oxalate of 
lime about it. 
There can be no doubt that the larger portion of 
the oxalic acid excreted, is manufactured within the 
"Ralfe, Morbid Urine, 7 
body. There have been those, however, who have 
disputed this. Owen Rees first elaborated the theory 
that oxalic acid is produced from the decomposition 
of uric acid outside the body. The discovery of oxal- 
urate of ammonium in the urine by Schunck. lent 
some support to this theory. Oxaluric acid is a de- 
composition product of uric acid, and is easily con- 
verted into oxalic acid ; hence it was inferred that 
uric acid transformed into oxaluric and then oxalic, 
was the source of oxaluria. Basham gives an excel- 
lent exposition of this theory of the causation of oxa- 
luria, in Reynolds's "System of Medicine."7 He there 
affirms in a very dogmatic manner, and with very 
scanty evidence, that " oxalate of lime, as a sediment 
in the urine, is of no other significance than that of a 
lithic acid diathesis." An excess of oxalate of lime 
in the urine meant for him an excess of uric acid in 
the system. It is an easy matter to demolish this 
theory. In the first place one of the cardinal doc- 
trines of Basham and his school, namely, that the ox- 
alurate of ammonium of the urine is changed to 
oxalate, was disapproved by Neubauer.8 He found 
that in progressive decomposition of the urine, the 
oxalurate of ammonium is changed directly into car- 
bonate of ammonium, and not into oxalic acid and 
urea. Oxalic acid has been found in the blood by 
Cantani and Garrod. This oxalaemia cannot be ac- 
counted for by Rees's theory. The explanation, ac- 
cording to this theory, of the origin of renal concre- 
tions of oxalate of lime, would be very difficult. It is 
exceedingly improbable that the decomposition of 
oxalurate of ammonium can take place almost instan- 
taneously after the secretion of a urine of normal re- 
action and perfectly free from every trace of ferment- 
i American edition, Vol. 3, p. 619. 
• Neubauer and Vogel. Analysis of the Urine. Am. Ed. p. 169. 8 
ation. Renal calculi of oxalate of lime, however, are 
very common. 
This is abundantly proven by the experience of Can- 
tani,9 who cites numerous instances. I have recently 
had under my own care a case of the kind. The gen- 
tleman had been a recent sufferer from renal colic, 
and had experienced several severe attacks. He had 
presumably been treated for lithuria. Upon examina- 
tion of the urine I found it loaded with oxalate of 
lime. The patient had luckily saved a calculus of 
about the size of a pea, that he had passed through 
the urethra. I found this, upon analysis, to consist 
almost wholly of calcic oxalate. I never found any 
excess of uric acid in the urine. If the urine and the 
calculus had not been carefully analyzed, it would 
have been natural to have considered the case one of 
lithiasis, and to have treated it accordingly. Oxalate 
of lime is probably a much more common cause of 
renal colic than is generally supposed; and for this 
reason the urine of patients afflicted with this disease, 
should always be carefully examined. Oxalate of 
lime may be found, indicating the cause of the painful 
paroxysms. 
Another fact disapproving the theory of Rees, and 
ne that, may not be generally known by the medical 
profession, is that oxaluria is common among horses. 
Williams 10 speaks of its occurrence in horses that are 
irregularly worked, like hunters, and those too 
abundantly fed with saccharine substances, as turnips 
and carrots. I have examined the urine of a number 
of horses and I have found oxalate of lime very fre- 
quently. In a stable containing five horses. I found 
abundant deposits of oxalate of lime in the urine of 
three of the inmates. In one instance the urine was 
9 Die Stotfwechselkrankheiten. 
10 Principlesand Practice of Veterinary Medicine, 3d ed., p. 419. literally loaded with it. The form of the crystals in 
this case was not the typical octahedral, but was a 
four-sided prism with pointed ends. This form is 
very rarely found in man, and might be easily mis- 
taken for other crystalline constituents of the sedi- 
ment, were not careful micro-chemical tests applied to 
reveal the true nature of the crystals. The horse ex- 
cretes a large amount of hippuric acid, but very little 
uric. We have no reason to suspect that the decom- 
position of hippuric acid is a source of oxalic acid. 
For these and other reasons the theory that the 
excreted oxalic acid is formed in the urine outside of 
the body cannot be sustained. We cannot affirm that 
oxalic acid is never formed during the decomposition 
of the urine, but we have abundant proof that this is 
not the ordinary cause of oxaluria. 
Some of the other theories to account for the pres- 
ence of oxalate of lime in tho urine are more prob- 
able. A conservative resume of these theories is 
given by Salkowski and Leube.11 They all have the 
common defect, that while they may seem to be suffi- 
cient to explain the occurrence of oxaluria in some 
instances, they are entirely inadequate to do so in 
others. 
The theory most commonly accepted is that the 
oxalic acid originates in defective metamorphosis 
within the body. Cantani is one of the ablest advo- 
cates of this theory. In his elaborate work upon the 
diseases of metamorphosis, he takes the ground that 
oxaluria is due to a condition akin to that of diabetes. 
He believes that the oxalic acid originates from the 
abnormal disintegration of the carbo-hydrates. There 
are many facts that lend probability to this view. 
The acid is very readily prepared in the chemical 
laboratory by the action of reagents upon sugar, 
9 
11 Lehre vom Harn, s. 419. 10 
starch, and cellulose. This fact would seem to render 
probable the possibility of its formation from the im- 
perfect oxidation of these substances in the body. Can- 
tani's mode of treatment for oxaiuria is based upon 
this theory. He states that the condition is especi- 
ally common in individuals indulging to excess in 
sweets and starchy foods. His treatment consists in 
very largely withdrawing these articles from the food 
and substituting an anti-diabetic diet. He claims to 
have permanently cured many patients in this way. 
But we find other recognized authorities maintain- 
ing that oxaiuria is the result of imperfect metamor- 
phosis of nitrogenous substances. This was Beneke's 
theory. It has been found that oxalic acid cannot be 
made to wholly disappear from the urine of fasting 
animals. 1 have found calcic oxalate quite abund- 
antly present in the urine of a patient subsisting en- 
tirely upon a moderate amount of milk-punch. 
Tyson 12 advises that in the treatment of oxaiuria 
the patient be allowed only a moderate amount of 
nitrogenous food, and in bad cases no meat at all be 
permitted. It would be hard to explain the good ef- 
fects of both Cantani's and Tyson's widely different 
modes of treatment upon the assumption that the 
theory of one alone is correct. Before endeavoring to 
reconcile the apparent incompatibilities existing in 
the views of these two authorities, it may be well to 
consider some of the other possible sources of oxalic 
acid in the body. 
Various authors have endeavored to trace a connec- 
tion between the formation of mucus and that of oxalic 
acid. Hoppe-Seyler 18 states that the crystals of ox- 
alate of lime are especially abundant in catarrh of the 
urinary passages, and of other mucous membranes. 
12 Boston Med. and Surg. Journal, Vol. 115. p. 365. 
13 Physiologisclie Chemie, s. 825. 11 
He also affirms that the connection between impaired 
respiration and the excretion of calcic oxalate has not 
been proven. Ralfe14 also accepts the possibility of 
the formation of oxalic acid from the decomposition 
of mucus, and gives considerable prominence to the 
theory. He states that crystals of oxalate of lime 
have been found in the mucus of the gall-bladder, and 
in the gravid uterus. Fiirbringer also found them in 
the sputum of a diabetic. Ralfe is inclined to the 
view that the numerous oxalate of lime crystals found 
in the urine of patients suffering from spermatorrhoea 
are derived from the mucus of the genito-urinary pas- 
sages. Ultzmann 16 has remarked the frequent asso- 
ciation of oxaluria and spermatorrhoea and urethral 
disease. He says that he has often caused the oxal- 
uria to disappear by local treatment of the urethra. I 
myself, have had several cases of true spermatorrhoea 
associated with oxaluria. I also recall another inter- 
esting patient who was troubled with an obstinate 
prostatorrhoea whose urine was loaded with calcic oxa- 
late. I have never, however, felt the necessity of at- 
tributing the oxalate of lime found in such cases to 
the presence of seminal fluid or mucus in the urine. 
The case that I have already mentioned of the gentle- 
man that had suffered from a severe renal colic is 
sufficient to demonstrate that there is not necessarily 
any reason for attributing oxaluria to the presence of 
semen in the urine. In the many specimens of the 
urine of this patient that I examined I never failed to 
find a large number of spermatozoa. These speci- 
mens were passed at different times of the day, some 
of them during my visits. The formation of the 
oxalate of lime calculus in the kidney in this case 
showed that there could be no direct connec- 
34 Loc cit. 
1S Die Harnconeremente. 12 
tion between the oxaluria and the spermatorrhoea. 
The crystals of the oxalate could be found very soon 
after the urine was passed, long before we could have 
any reason to suspect that any decomposition had 
taken place. The form of the crystals in this case 
was very suggestive. They were apt to be small and 
of irregular form, resembling those obtained by imme- 
diate precipitation upon the addition of a solution of 
oxalic acid to one of calcium chloride. They seemed 
to denote that the urine was surcharged with the 
oxalate and that many of the crystals were formed al- 
most instantly after the secretion or excretion of the 
urine. 
Although such cases as the above do not support 
the theory of the formation of oxalic acid from mucus, 
there are certain facts that render probable the possi- 
bility of such an event. It has been found by Land- 
wehr and by Hammarsten16 that a decomposition 
product can be obtained from mucin having the prop- 
erties of a carbo-hydrate. The further decomposi- 
tion of this carbo-hydrate, which Landwehr calls ani- 
mal gum (thierische Gummi) might yield oxalic acid. 
Behrens 17 calls attention to the frequency with which 
calcic oxalate is found in the vicinity of, or even in, 
slime-bearing cells of plants. Although it may not be 
fair to compare the slime of plants with the mucus of 
animals, there are points of similarity in some of the 
physical properties of the two substances. Plant 
slime, moreover, readily yields oxalic acid when 
treated with nitric acid. 
I think that, perhaps, I have already dwelt too long 
upon the conflicting theories that have been advanced 
to account for the formation of oxalic acid in the 
bodv. I can only briefly allude to others. The 
io Studien uber Mucin, etc., Pfliiger's Archiv, Bd. 36, s. 373. 
n Hilfsbuch zur AusfiilirungMikroskopischen Untersuchungen im 
botanischen Laboratorium, s. 210. 13 
theory of increased oxidation has been advocated to 
explain certain cases. The objections to the general 
application of the theory of impaired oxidation 
would apply to this one. Theoretically, perhaps, in- 
creased oxidation and metabolism with the formation 
of incomplete products, would explain some cases of 
oxaluria, but in default of experimental and clinical 
proof of the correctness of the hypothesis, we cannot 
profitably discuss it here. 
Among all the multitude of diseases and conditions 
in which oxaluria has been found there is one symp- 
tom or condition, and perhaps only one, that has been 
very constantly met with, namely indigestion. The 
frequent occurrence of dyspepsia and all the symptoms 
usually accompanying it with oxaluria has been often 
noticed by various writers. Some have been inclined 
to make the dyspepsia secondary to the oxaluria, 
others to make the oxaluria in some way dependent 
upon the dyspepsia. The acid theory was an out- 
growth of this last endeavor. It is well known that 
organic acids are oxidized in the body and converted 
into carbonic acid and water. It is fair to presume 
that impeded oxidation of the organic acids that are 
produced by fermentation in dyspepsia may end m the 
formation of oxalic acid. This theory would seem to 
account for the majority of cases of oxaluria better 
than any of those that we have hitherto considered. 
But there is another probable source of oxalic acid in 
the body which has been strangely overlooked. It 
has been assumed, nearly without exception, that the 
oxalic acid that originates here is formed either in the 
blood or in the substance of the organs and tissues. 
It does not seem to have occurred to the writers upon 
this subject that oxalic acid can be formed, like vari- 
ous other organic acids, in the alimentary tract. 
R riding. clinical observation and experiments have 14 
rendered it very probable to the writer that oxaluria 
may be due to this cause. Although I have consulted 
the literature of oxaluria quite extensively, I have 
only found one author who has alluded to this possi- 
bility. Chambers 18 hints of such an origin in the fol- 
lowing passage: " Chemists tell us that citric, malic, 
and other organic acids distributed through the vege- 
table world are liable to conversion into oxalic, so that 
it is not necessary that it should naturally be a con- 
stituent of the food eaten, but may arise during its 
fermentation or digestion." We are left in doubt as 
to whether the author means by this that the oxalic 
acid may be directly produced in the alimentary canal 
in consequence of abnormal fermentation, or whether 
from the imperfect oxidation, after absorption, of other 
products of fermentation. He contents himself with 
this bare allusion to the possibility of the manufactur- 
ing of oxalic acid from the food during imperfect di- 
gestion. Medical literature, however, has recorded 
many facts that lend great probability to this theory. 
Food that does not digest ferments, or decomposes, 
much in the same way as it would under similar con- 
ditions of warmth and moisture outside of the body. 
Decomposition and putrefaction play a part in the 
disintegration of the food in the intestines, even in 
normal digestion, and this part is a much more exten- 
sive one than is commonly supposed. Every phy- 
sician will be profited by reading the section in Her- 
mann's Handbuch der Physiologic, in which Maly 19 
describes the activity of bacteria in reducing the con- 
tents of the intestines to the condition that they have 
in the faeces. The intestines, particularly the lower 
portion of them, are swarming with bacteria. The 
faeces are filled with a great variety of micro-organ- 
'» Manual of Diet, p. 271. 
19 Pankreasfaulniss, Bd. V, Abth. 2, s. 218, 15 
isms. Any one can easily convince himself of the 
truth of this statement by microscopical examination. 
Given warmth, moisture, innumerable bacteria and a 
quantity of easily decomposable organic matter, putre- 
faction is inevitable, unless some substance be present 
to arrest the action of the bacteria. Bile is the nat- 
ural disinfectant of the intestines, but this is incapa- 
ble of preventing all putrefactive changes in the ali- 
mentary tract. Indican, one of the most constant 
constituents of the urine, is ever a witness of the in- 
sufficiency of this anti-fermentative action of bile. In- 
dican is derived from indol, and Maly states that there 
can be no indol or inflammable gas produced in the 
intestines without bacteria. He further affirms that 
the products of pancreatic decomposition do not have 
any physiological uses. 
Digestion is essentially a process by which insoluble 
substances are converted into others capable of being 
absorbed into the blood. True digestion is accom- 
plished in a relatively short time. Very likely, too, 
the digestive ferments may have some restraining in- 
fluence on the action of the bacteria. But when diges- 
tion is delayed, or is not accomplished, the micro- 
organisms present in the stomach and intestines assert 
their power; and we could scarcely devise more 
favorable conditions for the cultivation of bacteria 
than exist in the lower part of the intestines. That 
these bacteria manufacture, in many instances, very 
virulent poisons, has been abundantly proven by recent 
researches upon the subject of ptomaines. It is a con- 
stant source of wonder to one investigating the sub- 
ject that cases of poisoning of this origin are not more 
common than they appear to be. But, in all proba- 
bility, ptomaines are not the only poisonous sub- 
stances manufactured in the alimentary canal. Many 
organic acids are produced during the fermentation of 16 
food. Brieger 20 has isolated various species of bac- 
teria existing in the faeces, and has cultivated them 
outside the body. He also studied the action of these 
micro-organisms on fermentable solutions, and ob- 
tained, in this way, various organic acids. He does 
not record the finding of oxalic acid ; but it is not 
evident that small amounts of the acid would have 
been recognized by the methods of analysis that he 
employed. Investigations of this character are very 
important, and promise to shed a good deal of light 
upon questions of great physiological and pathological 
interest; and it is very desirable that this line of ex- 
perimentation be followed out. 
Fliigge places oxalic acid in his list of substances 
resulting from the activity of bacteria. If oxalic acid 
can be manufactured by bacteria outside of the body, 
it seems altogether probable that the same process can 
take place in the intestines. Salkowski21 states that 
crystals of oxalate of lime are not infrequently found 
in microscopical examination of the contents of the 
large intestine. He does not say what the probable 
origin of these crystals is. Either they must have 
been taken into the body in the food, or they must 
have been due to the combination of oxalic acid manu- 
factured in the alimentary canal with lime, unless we 
are disposed to admit that oxalic acid may be elimi- 
nated through the intestines, which seems in no way 
probable. We should also bear in mind that octahedral 
crystals of oxalate of lime, like those ordinarily found 
in the urine, are not common in plants containing the 
acid and its salts. The crystals in plants are apt to 
exist in irregular aggregations of these octahedral 
forms, or as needle-shaped crystals. We, therefore, 
have good reason to suppose that the oxalate crystals 
20 Zeitscliriftfiir physiologischen Chemie, Bd. VIII, s. 306, 
21 Salkowski und Leube, Lebre vom Harn., s. 114. 17 
found in the intestines are due to oxalic acid formed 
in the digestive organs. Of course, if oxalic acid is 
formed here, there is no reason why it should not be 
absorbed into the blood and give rise to oxaluria. I 
have made microscopical examinations of the faeces of 
several oxaluric patients. Although I have found 
octahedral crystals here, I have never been convinced 
by chemical tests that they were composed of oxalate 
of lime. For several obvious reasons, it is not a very 
easy matter to detect minute crystals scattered through 
such a mass of detritus as exists here. Such exam- 
inations, however, are promising, and should be re- 
peated. 
It seems to me, in the light of what has been said, 
that we have a right to assert that the theory of the 
formation of oxalic acid in the digestive organs is a 
very probable one. Several experimenters have un- 
consciously corroborated this theory. Fiirbringer22 
made an elaborate series of experiments to determine 
the influence upon the excretion of oxalate of lime of 
the ingestion of alkaline bicarbonates, lime-water, and 
uric acid and the urates. The results of these experi- 
ments were mostly negative. In one of his observa- 
tions, however, he casually records a great increase 
in the oxalic acid excretion coincident with diarrhoea. 
This occurrence is to me very suggestive. An ordi- 
nary diarrhoea means increased fermentation and pu- 
trefaction in the intestines. If oxalic acid has a source 
in this putrefaction, then the association of oxaluria 
and diarrhoea ought not to surprise us. 
Hammerbacher28 afterwards repeated some of these 
experiments of Fiirbringer, and investigated the effect 
of alkalies upon the excretion of calcic oxalate in 
dogs. He mingled enormous doses of bicarbonate of 
23 Deutsches Archiv. fur Klin. Med., Bd. 18, p. 143. 
22 Pfliiger's Arch., Bd. 33, p. 89. 18 
soda with the food of these animals, and found' that 
the amount of calcic oxalate in the urine was consider- 
ably increased. In one instance, at least, the large 
doses given caused vomiting and loss of appetite. 
The doses given ranged from five to twenty grammes. 
When we compare these weights with those of the 
dogs experimented upon, we see that the doses were 
excessively great. The digestion must have been pro- 
foundly disturbed by them. If the food did not digest 
it putrefied, and oxaluria was the result. This may 
not be the correct explanation, but it appears as prob- 
able as any that we can give. It does not, however, 
seem to have occurred to the author. 
Mills 24 performed some experiments upon a dog in 
" nitrogenous equilibrium," to determine the effects of 
various forms of diet upon the excretion of oxalic acid. 
He notes that a very large amount of the acid was ex- 
creted upon a dog following diarrhoea. The fact 
speaks for itself. 
I may add that oxalic acid is frequently found in 
the urine of hogs. Calculi consisting of almost pure 
calcic oxalate are sometimes found in the bladder of 
these animals. I have examined hogs urine only 
once; but in this instance I found a great number of 
calcic oxalate crystals, after allowing the urine to 
stand for a long time. When we consider the char- 
acter of the diet, and the habits and environment of 
these animals, we have every reason to suppose that 
bacteria have an especially attractive field of operation 
in their intestines. 
Williams 28 says that oxaluria in horses is apt to be 
accompanied by symptoms of acid-dyspepsia. The 
horses in which I have most often found oxaluria are 
those that are highly fed and little exercised : such 
M Journal of Physiology, Vol. V, p. 231. 
" Loo. cit. 19 
animals are, of course, specially liable to digestive 
troubles. 
Brunton 26 remarks that the deposition of oxalate of 
lime is usually connected with disturbances of the 
digestive system; and he further states that he has 
observed, in a hospital ward, that a deposit of this 
substance is commonly found in the urine after the 
patients have had cabbage for dinner. This occur- 
rence serves to strengthen the theory of the formation 
of oxalic acid from the decomposition of food. Prob- 
ably nothing would be more likely to afford an intes- 
tinal bacterium a greater opportunity for the exercise 
of its functions than an abundant supply of cabbage. 
The association of icterus and oxaluria has been 
noted by certain writers. Murchison27 thought that 
oxaluria might be connected in some way with liver 
trouble. As bile is the natural disinfectant of the it - 
testines, when its flow is obstructed decomposition can 
more readily take place. This would be a natural ex- 
planation of the occurrence of oxaluria with icterus. 
Indigestion means an increased opportunity for bac- 
teria- an opportunity that they are always ready to 
seize. 
The writer does not claim that the theory advanced 
here to account for the formation of, at least, some of 
the oxalic acid excreted from the body has been de- 
monstrated beyond controversy, but it certainly de- 
mands consideration. If it be true, then the treat- 
ment of oxaluria resolves itself into that of dyspepsia. 
26 Pharmacology and Therapeutics, p. 377. 
27 Functional Derangements of the Liver, p. 75.