300 



Charles Zeleny. 



Fig. 2 (x 216). 



Normal Larva Dez'chpcd from Whole Eggs. 



A, larva of 233^ hours, showing the beginning of the archenteric invagina- 

 tion. B, larva of 34 hours, showing enteron, mesenchyme cells and apical plate. 

 C, larva of 49 hours, showing apical plate, mesenchyme cells, enteron, and one 

 of the two lappets. 



size and position relations are preserved. The only abnormal case 

 is the irregular flat plate of seven cells shown in Figure 4C. When 

 therefore the cases are taken as a whole, the conclusion is very 

 evident that the experiments give no indication of a localization 

 of cleavage factors at this stage/ 



iJn connection with the early stages of cleavage the following subsidiary 

 points are to be noted: 



1. The nucleated fragments formed polar bodies as in the whole egg, while 

 none were formed in the non-nucleated fragments. 



2. No difference can be made out between nucleated and non-nucleated 

 fragments as regards character of the cleavage, each group showing similar 

 features as far as the limited data go. 



3. Probable polyspermy, as indicated by multiple division, was shown in 

 two eggs. 



4. The direction of the cut has no influence upon the character of the 

 cleavage. Of course, this necessarily follows from the conclusion as stated 

 above, that no localization of cleavage factors is shown in the group. 



