12 



yolk-spherules, are seen on one side of tke ovum, lying near the peri- 

 phery. These deutoplasmic masses, as they increase in size, do not at 

 first blend with one another, but preserve their individuality until the 

 ovum, having attained a diameter of about 1 ram, has become almost 

 completely filled with yolk-spherules. The yolk-spherules have an 

 endogenous origin. 



The vitelline membrane arises from a thin superficial layer of pro- 

 toplasm. 



The germinal dots , a little before the ovum attains a dia- 

 meter of 1 mm, begin to move towards the centre of the germinal ve- 

 sicle, and at the same time undergo repeated divisions. There is thus 

 formed a mass of small nucleoli, or fragments of such, in the centre of 

 the germinal vesicle. Later stages have not been completely made out. 



2. The Structure of the Ovary, and the Origin of the Eggs and 

 the Egg-strings in Nephelis. 



» By Mr. J. Jij ima, Tokio, Japan. 



The following is an epitomized account of the results of a study 

 on the genesis of the egg in Nejyhelis^. 



The ovary-wall consists of two layers, an external cell-and-muscle 

 layer (Tunica propria), and a lining epithelium. 



The proper tunic may be said to be composed of the following 

 4 strata, beginning with the external one. 



1) The circular muscle- fibres, which, running transversely, 

 completely encircle the ovarial tube, frequently anastomosing with one 

 another, and thus forming a muscular net- work. 



2) A stratum composed of rather loosely packed cells 

 and a net-work of vaso- fibrous tissue (Lankester), to- 

 gether with a few longitudinal muscle-fibres which run along the outer, 

 or what I have called, on account of its being thickened, the rachal 

 side of the tube. 



3) The semi-circular muscle- fib res, disposed in two 

 longitudinal series, one of which occupies the dorsal half of the 

 tube, the other the ventral half. The extremities of these fibres are placed 

 in the rachal and mediad lines of the tube. Except at the end of the 

 tubes, where they assume a longitudinal direction, these fibres have a 

 general transverse direction. They represent curves of double curva- 

 ture ; first they have the curvature of one half of the tube ; and se- 

 condly, a curvature facing anteriorly, which is formed by the bending 



' These observations were made in the Univei-sity of Tokio. 



