200 M. A. Stecker on the Development 



collect by degrees around the germinal vesicle (fig. I., g) ; whilst 

 the finer ones are uniformly distributed in the whole mass of 

 protoplasm, the true formative vitellus. The ovum is enve- 

 loped by a simple structureless membrane, the vitelline mem- 

 brane ; an external secondary membrane only makes its ap- 

 pearance subsequently. Even before this stage the ovum, r.e. 

 the protoplasm-mass of the ovum, becomes occupied by large, 

 clear globules of albuminous appearance (figs. I.-IV., pd), 

 which appear first at the pedicular pole, but then rapidly 

 accumulate round the germinal vesicle, which is situated in 

 the middle of the ovicell. Whether these spheres, which 

 we may call primary deutoplasm-spheres, originate from the 

 syncytium (Hackel) of the ovary *, is more than I can say, 

 as, notwithstanding all my endeavours, I could not trace their 

 formation ; the whole process takes place so rapidly, that the 

 whole ovum seems to be at once completely filled with these 

 deutoplasm-spheres. At the same time the limpid germinal 

 vesicle acquires a fusiform shape, until at last it is completely 

 surrounded by the primary deutoplasm-drops. A section 

 (fig. II.) through the ovum when in this stage will convince 

 us that around the vesicle of Purkinje (which, it may be 

 remarked in passing, gradually diminishes and finally disap- 

 pears altogether) a portion of protoplasm filled with numerous 

 fine granules has accumulated. In the middle, almost in the 

 place of the vanishing germinal vesicle, a round brown spot 

 now becomes visible, composed of the coarser granules of the 

 protoplasm ; this explains the concentration of the coarser 

 granules of the protoplasm from their first appearance in the 

 ovicell. 



In this stage of development a new, peculiar process com- 

 mences. A portion of the primary albuminoid deutoplasm- 

 drops gradually coalesce and become converted into a number 

 of strongly refractive deutoplasm-drops of fatty appearance 

 (we may characterize these formations as secowc^ar?/ deutoplasm- 

 spheres), which are, indeed, smaller than the primary deuto- 

 plasm-spheres, but soon so multiply that, even in a very short 

 time and whilst the volume of the ovum increases, it appears 

 completely crammed with the secondary deutoplasm-drops 

 (fig. III., s<]). A section made through the middle of the 

 ovum (fig. III.) would now show its composition to be as 

 follows : — In the middle of the ovum, instead of the Purkin- 

 jean vesicle, which has entirely disappeared, there is the round 

 brown nucleus consisting of coarser protoplasm granules, 

 which, as we shall see hereafter, play a very important part 



* Dr. Bertkaii, " Ueber den Generationsapparat der Araneiden." Archiv 

 fUr Naturg. Bd. xli. (1875) pp. 23.5-262, pi. vii. (see p. 245). 



