PLATE 21 



EXPLANATION OF FIGURES 



107, 108 (1090) Centrifuged 100 turns of hand machine before or during 

 second cleavage, fixed 18 hours later. The second cleavage was suppressed in 

 one blastomere (the lower) of figure 107 and in both of figure 108, and conse- 

 quently the micromeres are more or less abnormal in number and position. 



109 (1038) Centrifuged 100 turns of hand machine in 2-cell stage, fixed 4f 

 hours later. The second cleavage was very unequal, with the result that two 

 macromeres are large and two small. There are 18 micromeres, some of which are 

 difficult to identify. 



110 (1032, A) Centrifuged 2h hours during second cleavage, fixed 21 hours 

 later. Egg with four macromeres abnormally joined, and with two separate 

 areas of micromeres, which can not be individually identified with certainty. 



111 (1090) Centrifuged 100 turns of hand machine during second cleavage, 

 fixed 16 hours later. Two macromeres are large and two small. There are 

 24 micromeres, some of which are hard to identify. 



112 (1134) Centrifuged 30 minutes in 2-cell stage, fixed 21 hours later. 

 Macromeres arranged in a linear series, micromeres in two groups at opposite 

 ends of the egg. 



414 



