PLATE LIII. 



Effects of Diluted Sea Water. 



In figs. 132-135, 137-140, 144 the dilution was one part sea water to two parts fresh water; in all 

 other cases the sea water was diluted with equal parts of fresh water. With higher dilutions the blasto- 

 meres tend to separate but do not swell appreciably. 



Fig. 132. Exp. 875: Second polar spindle at animal pole; sperm nucleus has formed a spindle (o*Sp); 

 the homogeneous chromatic sphere below this may represent an accessory sperm nucleus (cfiV). 



Fig. 133. Exp. 875: First cleavage spindle; the seven chromatic spheres may represent accessory 

 sperm nuclei (<?N). 



Fig. 134. Exp. 875: Enormous second polar body containing large nucleus and yolk; two nuclei and 



accessory sperm nucleus ( c?A0 in egg. 



Fig. 135. Exp. 875: Probably J blastomere containing polyaster and with a micromere which has 



just divided. 



Fig. 136. Exp. 872: Three blastomeres showing reversed polarity, the spheres, nuclei and cytoplasmic 

 areas lying at the pole opposite the polar bodies; one sphere is found in each cell but in the two larger ones 



the nuclei are multiple. 



Fig. 137. Exp. 875: Two macromeres, one containing a triaster, the other a tetraster; the two micro- 

 meres are normal except for their large size. 



Fig. 138. Exp. 875: Similar to the preceding. 



Fig. 139. Exp. 875: Side view of an egg similar to figs. 137, 138. 



Fig. 140. Exp. 875: Macromeres A and B have not divided and the chromosomes are irregularly 

 scattered in the spindle; macromeres C and D have divided normally giving rise to first and second micro- 

 meres and the first set are subdividing normally. 



Fig. 141. Exp. 859: Chromosomes were scattered along the spindle during the third cleavage and 

 have given rise to chromatic connections between daughter nuclei, which resemble amitoses. 



Fig. 142. Exp. 872 : The micromeres are larger than usual (two of them contain yolk) and they have 



caused a separation of A, B, from C } D. 



Fig. 143. Exp. 872: The micromeres are larger than usual and contain yolk; the macromeres are 

 separated and one which has iust divided (Y. Y) contains yolk but no cytoplasmic areas; the chromosomes 



are here scattered along the spindle axis, thus forming a chromatic connection. 



Fig. 144. Exp. 875: \ blastomeres, each of which has given rise to one micromer 

 divided: the macromeres contain spindles along which the chromosomes are scattered irregularly 



i which has sub- 



