X2 G. O. Sårs. 



somewhat more opaque body. In the fish-eggs this body 

 represents the blastodisc, the remaining part the clear 

 nourishing yolk enveloped by the normal egg-membranes. 

 In the oosphères, on the other hand, the inner small body 

 represents only the egg proper, whereas the surrounding 

 sphere does not form, strictly speaking, an integrant part 

 of the egg, but only a simple suspensory capsule destined 

 to keep the egg floating in the sea. While the blastodisc 

 in the fish-eggs is always more or less flattened, attaining 

 its strongest convexity immediately after the segmentation 

 process is finished, the inner body of the oosphères exhibits 

 in all stages a perfectly globular form, and is surrounded by 

 a distinct, thin membrane. It is about 0.40 mm. in diameter, 

 and does not seem to be fixed in any manner, but is simply 

 suspended within the fluid of the sphere sinking by its own 

 weight to the bottom of this. Messrs. Brook and Hoyle 

 say that the external envelope showed itself to be doubly 

 contoured under a high magnifying power. This, I think 

 must be due to a misconception; for I have convinced my- 

 self that the surronding membrane of the sphere is quite 

 simple, and extremly thin and flexible, so as to be easily 

 penetrated. As to the fluid contained within the sphere, it 

 does not seem to exhibit any difference from the sur- 

 rounding medium, and it retains its original transparency quite 

 unaltered in spheres that have long been preserved in strong 

 alcohol, whereas the most transparent fish-eggs very soon, 

 in such cases, assume a rather opaque appearance, on account 

 of the coagulation of the vitelline matter. I have not been 

 able to detect any distinctly defined opening in the outer 

 membrane; though I believe that it admits of being pene- 

 trated not only by fluids, but also by very small cellular 

 bodies. Indeed, in some cases I have found in close approxi- 



