51 

 coine less easily recoFj-iized. 



The second cle:nvage occurs r.bout tv/e'^ty-i'ive or "thirty 

 rai-iut?s after the first. The -lane of division is also 

 meridional and at right angles to the first seg-.entation. 

 It begins =^* to the centre of the egg next to the furrow of 

 the first cleavage and slowly extends out toward the neri- 

 phery. "hen the division the four blastoireres 

 u-dergc a slight rotation froT righ'u to left; a^d i'^ the 

 centre of the egg betv/een the cells there is^ at tir.es^ to be 

 seen a srr.all onen s- ace or seg-.entation cavity v/hich -^.ay 

 extend through the entire egg as shov;n in Figure 12. 



After a lanse of tine ecual to that v.-hah occurs between 

 the first and second divisions, the third cleavage furrov; 

 arrears. This nlano of division is equatorial and divides 

 the egg into eight blasto-eres. ihen the sf:gnentation is 

 first coTT^nleted t-he two ouartets of cells are' situated one 

 upon the other and forr a ''ore or less s'^herical v/hole, 

 as is the usual arrangement in eggs in which segi^u-ntatioh 



