MARGARET R. MURRAY. 



metabolic significance. Essentially the same appearance is pro- 

 duced by impregnation with osmic acid (Figs. 5, 6): granules 

 are not seen "within the plasmosome, but form a sharp cortical 

 sheath around it. In Champy preparations (Fig. 3), black 

 granules are seen on the plasmosome, as well as surrounding it. 

 (Here the plasmosome also contains clear yellow granules, 

 somewhat larger than the black ones.) With scharlach R after 

 formol, granules sheathing the nucleolus and scattered in the 

 nucleus stain orange. 



These observations seem to indicate a sequence or meta- 

 morphosis of granules from nucleolus of follicle cell to yolk of 

 egg, with the mitochondrial state as one stage in the sequence. 

 \Yhen they have reached the egg cytosome, the granules probably 

 affect in some way the condition, or perhaps the synthesis of 

 the other types of yolk globules, which they invariably surround. 

 (Cf. Gatenby on Insect Ovogenesis.) It would, of course, be 

 very .desirable to see this process going on in the tissue cultures. 

 This was attempted without success. It seems possible to 

 attribute the failure partly to the opacity of the follicle cells 

 (it was impossible to use either camera lucida or projection 

 microscope on the small granules in order to detect motion over 

 a long period of time) ; and partly to the extreme slowness with 

 which the process must take place (August to November to 

 produce the two to three cubic milimeters of yolk which are 

 found in a mature egg). 



3. Yolk Globules. 



The arrangement of yolky materials in the oocyte is a very 

 definite one, as illustrated by the figures, especially Fig. i, 

 which represents an area extending from the external follicular 

 membrane to the longitudinal axis of the egg. The yolk globules 

 are oriented in the pattern indicated, with reference to the 

 periphery of the egg, that is, with reference to the follicle cells. 

 The nucleus of the egg is often distinctly eccentric, but that 

 does not alter the arrangement of the yolk with reference to the 

 follicle. Besides the small mitochondrial, or fuchsinophile, 

 granules already referred to, the egg cytosome contains two 

 types of globules. One of these, which will be referred to as 

 the "large" type of globule, is at its maximum size a short 



