March 16, 1953

Dear Ralph:

Thank you for your letter of the llth. Had I known you could be pro~
vokeé into thinking about these questions, I would have done either of two
things a) sent you the as. beforehand, to help avoid error, or b) thrown
some mere in (purposely) for piquance.

Seriously, I think you will agree that the whole subject is quite murky,
(and I am rather out of my depth in the phycological aspects of it), but that
some kind of generalization has been needed in order to help organize more
interest in it. I trust my mistakes will not have led anyone seriously astray,
You will have to keep in mind also that I have had to quote many assertions
ct their own yaue, without necessarily forming my own definite conclusions

@.g. your #1}.

Ae to 2} phagotrophy is not the full answer; 1t does show how an endo-—
sypbiont can get inside the outer limiting wall. I can appeal only to the
reeshablishment cf the chlorella--Paramecium bursaria symbiosis as, perhaps,
supporting this kind of view.

3): Ido not disagree, The presentation of these as likely symbionts,
following Pascher, seemed the line of least resistance; it is by no means
unqualified, I am interested to hear you have actually worked with Cganophora.
Bo you have this in culture? Is it easy enough material to handle to warrant
using it dn this kind of study?

&) Wy slip! whet would you have recommended as a correct term for ny
obvious inéant?—mlorcoflorad doesn't sound quite right.

5) I didn't invent these usages of "chromogenic" béth are reasonably
well established but it hadn't occurred to me that I had used both. (Cr.
J. Bact. 601381; JBC 170:391; Lindegren, CSH 1946). Of course, the nouns are
chromogen and chromogene, respectively, sc there should be less trouble with
these.

6) Englesberg and Davis are, if not dachnotrophic, irrepressible, while
Horowitz is, at least, prototrophic. _ a

Sincerely,

Joshua Lederberg