66 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



existed, that there must exist, a sort of intimate structure 

 in the egg, including polarity and bilaterality as the chief 

 features of its symmetry, a structure which belongs to 

 every smallest element of the egg, and which might be 

 imagined by analogy under the form of elementary magnets. 1 

 This hypothetic structure could have its seat in the proto- 

 plasm only. In the egg of echinoderrns it would be capable 

 of such a quick rearrangement after being disturbed, that 

 it could not be observed but only inferred logically ; there 

 might, however, be cases in which its real discovery would 

 be possible. Indeed Eoux's frog-experiment seems to be 

 a case where it is found to be at work : at least it seems 

 very probable to assume that Eoux obtained half of a 

 frog's embryo because the protoplasm of the isolated blasto- 

 rnere had preserved the " halfness " of its intimate structure, 

 and had not been able to form a small whole out of it. 



Of course it was my principal object to verify this 

 hypothesis, and such verification became possible in a set 

 of experiments which my friend T. H. Morgan and myself 

 carried out together, 2 in 1895, on the eggs of ctenophores, 

 a sort of pelagic animals, somewhat resembling the jelly- 

 fish, but of a rather different inner organisation. The 

 zoologist Chun had found even before Eoux's analytical 

 studies, that isolated blastomeres of the ctenophore egg 

 behave like parts of the whole and result in a half-organisa- 

 tion like the frog's germ does. Chun had not laid much 

 stress on his discovery, which now, of course, from the new 

 points of view, became a very important one. We first 

 repeated Chun's experiment and obtained his results, with 



1 But the elementary magnets would have to be bilateral ! 

 2 Arch. Entiv. Mech. 2, 1895. 



