8 Transactions of the Society. 



denoted by the letters Ya, Yh, Yc, Yd and Y., the last being the 

 completed yolk sphere. In this cell mitochondria are to be seen 

 scattered throughout the cytoplasm. 



When each yolk sphere is completely formed, the investing 

 sheath of Golgi elements begins to break up, and the fragments 

 pass eithei- outwards to the periphery, where they form a layer 

 under the vitelline membrane, or else towards the nucleus, around 

 which they form a covering. The breaking away of the Golgi 

 elements is shown in tig. 11, which also shows the collecting of 

 the fragmented portions at the periphery. At fig. 12 is shown a 

 portion of the periphery of a full-grown egg. The yolk bodies are 

 all much the same size ; between them are mitochondria and 

 fragmented portions of the Golgi apparatus, and similar pieces are 

 seen forming layers underneath the egg membrane and around the 

 nucleus. Fig. 11 shows a similar portion of an egg from which 

 the fat has been dissolved. It is here .seen that although the 

 greater part of the Golgi elements have become dispersed from the 

 peripheral yolk bodies, yet a few batonettes still remain attached. 

 In no preparation examined have I found eggs in which the whole 

 ''of the apparatus elements have been broken away from the yolk 

 bodies. 



The Mitochondria. 



The chondriome or mitochondrial complex of the cell is 

 represented in the youngest 0(')cytes by several irregular-shaped 

 masses which stain a deep black with iron ha'matoxylin after Fleni- 

 ming- without- acetic fixation, or red with acid fuchsin after fixing 



EXPLANATION OF PLATE II. 



Fig. 9. — Older oocyte than that in fig. 8, showing the behaviour of the Golgi 

 elements (GE.l-GE.d) during yolk formation. Chondriome granules are seen 

 dividing to form mitochondria (^I.). Ditto. 



Fig. 10. — Portion of the periphery of an older oocyte, showing the formation 

 of yolk spheres (Ya-Y.) at the periphery of the cell. Ditto. 



Fig. 11. — Portion of the periphery of a full-grown oocyte, with a peripheral 

 layer of fragmented Golgi elements (GE.) and yr Ik spheres (Y.), with portions of 

 the Golgi aj)paratus still adhering ; fully-grown mitochondria in the cytopla.sm. 

 M.K.A. with turpentine. 



Fig. 1-2. — Peripheral region of a full-grown oocyte untreated with turpentine, 

 drawn under a lower power than fig. 11. 



Figs. 13, 14. —Young oocytes slightly older than that shown in fig. 2, showing 

 the chondriome granules (CH.) and the temporary follicle of nurse cell (NC). 

 F.W.A. and iron htematoxyliu. 



Fig. 15. — Oocyte at about the same stage of development as shown in fig. 8, 

 showing the yolk spheres (Y.) scattered in the cytoplasm and the mitochondria 

 (^I.) beginning to spread out in the cell. F.W.A. and iron haematoxylin. 



Fig. 16. — Older oocyte, with fairly evenly-distributed yolk spheres (Y'.) and a 

 number of centres of actively-dividing mitochondria (M.). F.W.A. and iron 

 htematoxylin. 



Fig. 17. — One of the groups of actively-dividing mitochondria (M.) shown in 

 fig. 16, under a higher power. F.W.A. and iron haematoxylin. 



