PARASITISM AND SYMBIOSIS CAULLERY. 403 



a few months ago, by Mr. P. Portier of his book Les Symhiotes has 

 once more brought this question to attention. While not stating it 

 in a really new manner, but rather by bringing forward hitherto- 

 expressed ideas in new associations, Mr. Portier has wished to show 

 in his book that symbiosis is a widespread phenomenon, one of the 

 fundamental bases of the life of cellular organisms. The cell, indeed, 

 universally regarded by biologists at present as the fundamental and 

 indivisible unity, would be, according to this view, a symbiotic asso- 

 ciation; the cell strictly speaking, such as we conceive it, would be 

 by itself unable to subsist, if, in its interior, it did not contain sym- 

 bionts, bacteria having the power of direct assimilation, a power 

 which they use for the good of the cell as well as of themselves. And 

 Mr. Portier believes he has recognized these symbiotic bacteria or 

 bacterioids in the organites studied in histology under the name of 

 mitochondria. There would thus be two classes of beings : The bac- 

 teria, sufficient to themselves, autotrophes according to Mr. Portier's 

 expressive terminology ; and cellular organisms, assimilating through 

 the intermediary of the symbiotic bacteria, Iieterotrophes in the same 

 terminology. Without going further we can see the capital impor- 

 tance of such conception. It would bring about, as its early partisans 

 said, a renovation of the fundamental concepts of biology comparable 

 in importance to the revolution due to the ideas of Pasteur. But 

 however clear and suggestive this conception may be, it has no value 

 except in the event that the facts verify it; it must be seen in what 

 measure Mr. Portier has justified the affirmation which he has made 

 in a decisive form. This will be one of the questions which, later in 

 our course, we shall examine at our leisure; making allowance for 

 the discussion which I shall arouse, I do not hesitate now to declare 

 formally that in my opinion the proof is in no way furnished by 

 the author, and that, on the contrary, his argument can be met by 

 objections of fundamental importance. I declare this without hesi- 

 tation, but I recognize that I shall have the burden of proving what 

 I assert. 



From the physiological point of view the study of parasitism 

 touches on numerous other questions. For a parasite there is always a 

 more or less definite relation to a particular host, a relationship which 

 sometimes becomes exclusive. Thus Gonosyora longusima, a gregar- 

 ine which Mr. Mesnil and I have studied, 1 is always present and 

 abundant in one of the forms of Dodecaceria concha?*iwi, the form 

 which we have designated as B; it is never found in form A; and 

 yet these two forms represent a single species of annelid, or two 

 species which are very nearly related. Many given species of entomo- 



1 Caullery et Mesnil, Les fonnes 6pitoques et revolution des Cirratuliens, Ann. Univ., 

 Lyon, fasc. 38, 1898. 



