354 Messrs. Koren and "Danielssen on the 



They are frequently very delicate and transparent, especially 

 when they have not long been deposited. It is then very easy 

 to observe the eggs which are enclosed in them. The capsules 

 which have hitherto served for our observations were freshly de- 

 posited, so that we were able to follow the development in all its 

 stages. 



Each capsule is filled with a viscous humour, as transparent 

 as water, and resembling white of egg ; it contains a multitude 

 of eggs (from 600 to 800). The latter vary a little in volume, 

 from 0'257 to 0*264 millim. ; and each of them, as we for- 

 merly stated*, is furnished with a delicate chorion and with a 

 vitelline membrane closely surrounding the vitellus, which is 

 composed of large or small granules, of a nearly round form, 

 and of the vitelline liquid [liquor vitelli). The large granules 

 are clear, of a more oval form, and refract the light strongly ; 

 they appear to be of an oily nature. The small granules are all 

 of a dark colour, and round ; they are scattered amongst the 

 larger ones. We have found no germinal vesicle, but at the 

 position ordinarily occupied by this, the vitelline mass was still 

 clearer, and in the midst of this [clear] mass we perceived a little 

 clear vesicle. 



The first transformation of the eggs was, that the small clear 

 vesicle, of which we have already spoken, approached the peri- 

 phery of the vitellus, where it could be more easily seen. It 

 extended itself over the vitelline mass, and formed upon it a 

 spherical eminence, which was covered by the vitelline mem- 

 brane ; it had a rounded form, was as clear as water, and con- 

 tained two or three molecules. 



Some days afterwards, we remarked that the eggs had ap- 

 proached each other more closely, that the clear body had 

 advanced still more over the vitellus, and that it had not only 

 pushed the membrane before it, but had at the same time 

 extended the chorion, so that the latter formed an arch. On 

 the eighteenth and nineteenth days, the capsules have usually 

 become a little altered; they are rather clearer at the up- 

 per part, the eggs having slipped down to the bottom of the 

 capsule. 



The enclosed liquid was not so viscous as before, and the 

 clear body, in many eggs, had traversed the chorion and be- 

 come dispersed in the liquid; whilst, in others, it was still 

 united with the vitellus by a slight pedicle, formed by the vitel- 

 line membrane. In these the chorion was much enlarged, and 

 ruptured at the highest point. In the pedicle there were no 



* Here, as in many other places, we must refer the reader to our pre- 

 ^ous investigation of the history of the development of the Pectini- 

 branchiata. 



