14 Art. 3,-Xaoliide Yatsu : 



operation was performed at a later stage (PI. IV, Figs. 51, 52) a 

 new accumulation of the ectoplasm appeared at the end of the 

 incision which reinforced that of the old "cleavage head" to form 

 the new one. The resulting cleavage furrow was exactly the same 

 .as that in the foregoing case. 



In five cases the new '^ cleavage head " was formed on the 

 side with more cytoplasm, while in one case it was just reverse. 

 This may be interpreted in two difïerent ways, viz., (a) that a new 

 •cleavage furrow is formed on the side of more cytoplasm, or 

 (b) on the side of more ectoplasm or "cleavage head ''-substance 

 •due to oblique section. The above experiment fails to decide 

 -which of the alternatives is the correct view. The following 

 «experiments were especially directed to this point. 



g) Experiment I'll (One cass). 



The "cleavage head" was split vertically and a nucleated 

 portion was cut off as is shown in Fig. 52 (PI IV). A new cleavage 

 furrow was formed at an angle to the old and on the side of more 

 •cytoplasm. 



h) Experiment VIII (Three cases). 



For the same purpose, the ' ' cleavage head ' ' was split and a 

 portion of the cytoplasm was cut off. In all cases as in Exp. VI a 

 new "cleavage head" ajopeared at some angle to the old one. 

 In one case a new division plane was directed towards the cut sur- 

 face (PI. IV, Figs. 55, 56) while in the other two the \\q\y furrow 

 was formed on the side of the larger cytoplasmic mass and turned 

 upwards as in some cases in Exp. Ill (PI. IV, Figs. 58, 59). 



This experiment clearly shows that the new " cleavage head" 

 develops on the side of larger cytoplasmic portion. 



i) Experiment IX (One case). 



In one egg the "cleavage head" was split and another 

 incision was made on one side of it (PL IV, Fig. GO). A new 

 ■" cleavage head " was formed on the left hand side which turned 



