552 H. S. Jennings and George T. Hargitt. 



as well as the new races produced — if we ask the question: In 

 how many cases does he claim to have seen new races produced? 

 — the number falls at once to at most six. Let us examine these. 

 1. The first case ('09, p. 144-145) relates to Stentor. Here 

 condition no. 1 was not fulfilled, since the author nowhere states 

 that the culture was derived from a single individual. As to con- 

 dition no. 2, at first reading one gets the impression that this was 

 fulfilled, but a more careful study shows that it was not. The 

 facts are set forth as follows : " In a Stentor culture that I had 

 set in progress for various experiments and that I looked through 

 carefully everyday, there appeared from time to time, although 

 seldom, a few Stentors, which were at once noticeable on account 

 of their smaller size. . . . All these small Stentors were th e 

 product of chance inequalities in fission" (p. 144). This latter 

 statement would seem to cover our second requirement, till we 

 inquire as to the basis on which it is made. The author states 

 "These irregular divisions I was able to observe in a few cases" 

 ("ein paarmal") (p. 145). The statement that all were due to 

 such unequal divisions is thus an assumption ; the question of im- 

 portance is whether he observed the unequal division and iso- 

 lated its products in the particular case where he believes that two 

 diverse races resulted. On this point again the first general im- 

 pression is that he did, for he says, "On November 11, 1907, I 

 separated from the main Stentor culture a small animal that had 

 arisen through unequal fission" (p. 145) — but again careful 

 examination of the text shows that he did not observe this unequal 

 fission but merely assumes it, for he gives an extract from his 

 note-book as to the first appearance of this small specimen, where 

 fission is not mentioned at all. It is simply this: "11. XI. 07. 

 A small Stentor coeruleus. Nucleo-plasmar relation normal." 

 Now this small individual was cultivated separately, and its 

 progeny retained the small size. But since the original culture 

 is not stated to have come from one individual and since the au- 

 thor does not say that he observed the fission by which the small 

 specimen arose, and since he did not isolate and cultivate the other 

 product of the supposed unequal fission to see if it was larger — 

 it is possible, indeed probable, that the original culture contained 



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