EGGS AND LARVAE OF TELEOSTEANS. 



133 



in this plane will be that represented in fig. 2. The two nuclei will be seen 

 projected on to the focus-plane as at n l n 2 , fig. 2 ; while the under surface of that 

 part of the blastodisc, which is nearer to the observer, will be projected on to 

 the focus-plane as a curved line, apparently dividing the blastodisc into 

 two portions, one internal and one external, each containing one of the nuclei. 

 In PI. III. fig. 8, the blastodisc is seen thus apparently divided before the first 

 division has taken place, but the dividing line is nothing but the under surface 

 of the near part of the blastoderm projected on to the focus-plane. A com- 

 parison between the diagram in fig. 2 and figs. 4 and 12, pi. iii. of Hoffmann's 



a 



y 



i 



Fig. 1. Fig. 2. 



memoir, will show how completely his views are explained by my supposition. 

 At the same time all his figures cannot be so explained. Figs. 2 and 4 of his 

 pi. v. are in direct opposition to my results. 



It is a remarkable fact that, as will be evident from a reference to PI. IV. 

 fig. 3, the nuclei of the two-cell stage are not at first in the thickest part of their 

 respective cells. The centre of aggregation of the protoplasm lies nearer the 

 edge of the blastoderm than the nucleus, and it would seem as if the protoplasm 

 were active in the division and the nucleus passive, a hypothesis quite contrary 

 to current conceptions. I have been unable to find any evidence of the exist- 

 ence of periblast up to the eight-cell stage. PI. IV. fig. 5, shows an optical 

 section of the four-cell stage, in which it is evident there is no separate sub- 

 blastodermic layer. 



