310 APPENDIX A 



Lillie has shown (Journ. Exp. Zool. iii. 1906) that in the egg of 

 Chaetopteriis there are granules of different kinds which pass, in 

 segmentation, into definite cells. By means of the centrifuge 

 some of these the endoplasmic may be driven to one side of 

 the egg, but in whatever position these organ-forming granules 

 may be thus artificially placed, the cleavage has the same relation 

 to the egg axis (as determined by the polar bodies) as in the 

 normal egg. The factors of cell-division are thus separable from 

 those of differentiation. 



To the cases quoted in the summary on pp. 245, 246 might be 

 added the various instances in which an egg may be made, by 

 heat or pressure or shaking, or in artificial parthenogenesis, to 

 segment abnormally and yet give rise to a normal larva. 



