DEVELOPMENT OF EGG FRAGMENTS IN CEREBRATULUS. 1 2Q 



Summary : 



Perfect pilidia 6 24 % 



Defective pilidia 20 76 % 



important to observe that most of the perfect larvae were pro- 

 duced from the egg cut along CD. The basis of the apical 

 organ must, therefore, have existed below the line CD. This 

 fact, and the frequent occurrence of a defective apical organ in 

 series B taken together, it may safely be concluded that the basis 

 of this organ takes the form of a broad ring a little above the 

 equator. But how it finally takes an apical position I am at a 

 loss to imagine. Although Professor Wilson's experiments 3 were 

 not directed to this problem, his results seem to tally well with 



1 In this egg the nuclei conjugated in the vegetative hemisphere ; the section 

 plane passed nearly through the equator. 



2 In this egg the sperm-nucleus must have been present in the piece which I 

 thought enucleated. 



3 Wilson, /. f., pp. 432, 433 (Fig. 10), 436. 



