EAELr DEVELOPMENT OP JULUS TEBEESTRIS. 223 



matin granules which are present in small numbers (fig. 15). 

 Within the deeply staining nucleoluSj several vesicular spaces are 

 present. I am unfortunately unable to read Russian, but from 

 an examination of the figures of a Russian paper by Repiakoff, 

 published in 1883, on the development of Geophilus, I imagine 

 that the ovum of Geophilus at this stage is of similar structure. 



I have been unable to observe anything of the impregnation 

 of the ova, which probably takes place immediately before 

 deposition. 



My earliest stages occur late on the same day on which the 

 ova are laid ; sections through such ova show (fig. 3) that the 

 protoplasmic network and yolk-spherules remain as before, but 

 the nucleus is no longer at the periphery, but is situated in a 

 mass of protoplasm in the centre of the ovum. This mass of 

 protoplasm is of irregular shape, but its long axis corresponds 

 with that of the ovum. Prom it amoeba-like processes radiate 

 in all directions, forming a protoplasmic network throughout 

 the egg (fig. 17, a, b). The nucleus is no longer a distinct 

 vesicle, but its position is marked by the chromatin granules 

 alone. There is no nucleolus. 



Early on the second day the nucleus and the central mass of 

 protoplasm divide into two parts. The division of the proto- 

 plasm is not, however, complete, the two resulting masses with 

 their nuclei remaining connected by a network of protoplasm. 

 This is shown in figs. 4 and 16. The two first segmentation 

 masses separate till they are some distance apart, though still 

 connected by strands of protoplasm ; they then divide, so that 

 we now have four segments all connected together. This pro- 

 cess is carried on until there are a considerable number of 

 these segmentation masses present, and early on the third day 

 the first formation of the blastoderm begins. At the close of 

 segmentation the ovum consists of a number of these segmenta- 

 tion masses, resulting from the division of the original central 

 mass of protoplasm. Each of these masses has a dense central 

 portion, in which is situate the nucleus, while the outer portion 

 is broken up into innumerable processes, which connect the 

 masses together and permeate the yolk in every direction. 



