DIFFERENTIATION, HEREDITY, SEX 



283 



may be of different species, in somewhat different stages of 

 development, and no micromeres included in the mass 

 (Garbowsky). 



FIG. 134. Normal but diminutive larvae of Echinoderms, derived from por- 

 tions of gastrulse. From Jenkinson, after Driesch. a. Normal pluteus of 

 Sphcer echinus, b. Pluteus of same from portion of gastrula. c,e. Normal 

 bipennaria of Asterias glacialis. dj. Bipennaria of same, from vegetative half 

 of gastrula. g. Larva of Asterias with typical three-parted gut, but no ccelom, 

 from vegetative half of gastrula, removed after development of the coelomic sacs. 



While such results as these are at first sight opposed to the 

 hypothesis of germinal localization, yet it is quite possible to 

 reconcile the differences between such extreme forms as the 

 Echinoderms, where one of eight or sixteen cells finally forms a 

 typical larva one-eighth or one-sixteenth normal size, and the 



