136 Animal Life and Intelligence. 



first sight seems to be by organic analogies, it finds to-day 

 but few adherents. With all our increased modern micro- 

 scopical appliances, no one has ever seen the production 

 of gemmules. Although it appears sufficiently logical to 

 say that, just as a large organism produces a small ovum, 

 so does each small cell produce an exceedingly minute 

 gemmule ; when closely investigated, the analogy is not 

 altogether satisfactory. It is denied, as we have seen, by 

 many biologists that the organism does produce the ovum. 

 Multiplication is normally by definite, visible cell-division. 

 Nuclear fission can be followed in all its phases. But 

 where is the nuclear fission in the formation of gemmules ? 

 It is true that the conjugation of monads is followed by 

 the pouring forth of a fluid .which must be crowded with 

 germs from which new monads arise, and that these germs 

 are so minute as to be invisible, even under high powers 

 of the microscope. It might be suggested, then, that in 

 every tissue some typical cell or cells might thus break up 

 into a multitude of invisible gemmules. But there is at 

 present no evidence that they do so. And even if this' were 

 the case, it would not bear out Darwin's view, that every 

 cell is constantly throwing off numerous gemmules. It is 

 known, however, or at least generally believed, that there 

 is a constant replacement of tissues during the life of the 

 organism. It is said, for example, that in the course of 

 seven years the whole cellular substance of the human 

 body is entirely renewed. The fact is, I think, open to 

 question. Granting it, however, it might be suggested 

 that the effete cells, ere they vanish, give rise to minute 

 gemmules, which find their way to the ova. But it must 

 be remembered that the new tissue-cells in the supposed 

 successional renewal of the organs are the descendants of 

 the old tissue-cells; that these are, therefore, already 

 reproducing their kind directly ; and that the formation of 

 gemmules would thus be a special superadded provision 

 for a future generation. Still, there is no reason why cells 

 should not have this double mode of reproduction, if any 

 definite evidence of its existence could be brought forward. 



