Conf7'ihutions to the Study of the (Jugenesia of Patella. IL 



acquire typical granular form. Yolk bodies are probably formed 

 the same way as in Liinmva and Patella. 



The earliest stages in the development of the mitochondria of 

 Patella are very similar to what has been described in Ascidian 

 oocytes by Hirschler (.9). He finds in the youngest oocytes round 

 oval granules which comprise the chondriome or niitoch(jndrial 

 complex of the cell. They are coloured red in Mann-Kopsch 

 preparations stained by Altmann's method. These bodies increase 

 in size, and at their peripheries granular mitochondria appear and 

 spread out in the cytoplasm. While this is taking place stalk-like 

 processes arise connecting the chondriome bodies with the nuclear 

 membrane, and it seems that some substance passes out from the 

 nucleus along the stalks into these bodies, as at their centres, which 

 are capsule-like at this stage, granules are seen which resemble 

 the fine granules of the nuclear network. 



From the chondriome bodies arise also yolk nuclei. They 

 attain their maxinmm size before the Golgi elements begin to 

 spread out in the cell ; then as these latter organs begin to 

 disperse the nuclear stalks Ijreak. down and the yolk nuclei 

 disintegrate and eventually disappear altogether. In Patella the 

 mitochondria appear to develop as the result of the breaking up of 

 the granular bodies seen in the youngest oocytes ; there are no 

 connecting stalks seen between these granules and the nucleus. 

 It is interesting, however, to note that there is an extrusion of 

 solid nucleolar substance into the cytoplasm. 



The Golgi apparatus is described by Hirschler in the Ascidian 

 oocyte as at first consisting of five or fewer granules. They increase 

 in size and collect into small heaps, and eventually become joined 

 together by black threads to form a complex net-like body, which 

 he terms the complex stage. Hirschler sees in this the prepara- 

 tion for a nuclear division which does not take place. He quotes, 

 in support of his views, the researches of Deinecka, who showed 

 that in young nerve cells capable of division, and also in tlie 

 meristematic cells of pavement epithelia, the Crolgi apparatus is in 

 the concentrated condition, while in older cells incapable of division 

 it is in the diffuse state. 



When the ' volk nucleus ' lias reached its maximum growth 

 and the mitochondria are being dispersed in the cell, the Golgi 

 api aratus breaks up to form a small cloud of particles about the 

 size of a mitochondria, but distinguished from them in the Mann- 

 Kopsch preparations by the difference in colour. The individual 

 Golgi elements extend throughout the cell and decrease in numljer 

 towards the end of oogenesis owing to their conversion into yolk. 

 Individual elements fuse with swollen mitochondria to form a 

 complex yolk body. 



In Ascidian oocytes, then, according to Hirschler, we have a case 

 of the Golgi element itself being converted into yolk. This also 



