DEPARTMENT OF EMBRYOLOGY. 107 



changes in position. The most common and stable form is spherical, 

 and such vacuoles may remain unchanged for a long time. Some send 

 out thread-Uke processes or channels which contain the same fluid as 

 the vacuole, and these anastomose with other channels and form a com- 

 plicated plexus. While much the same size and shape as the mito- 

 chondria, these channels change much more rapidly and, with staining 

 reactions such as were used, there is no difficulty in distinguishing 

 them. The granules move about actively with the cytoplasmic cur- 

 rents, usually in paths between the periphery and the centrosphere. 

 At first scattered, they gradually increase in number and tend to 

 accumulate at what appears in the early stages to be a given point. 

 In the fixed preparations and in older cultures it is clearly seen that 

 this point is about the centriole or centrosphere. Because of its bearing 

 upon cell metabolism, it is an interesting and important point that the 

 centriole and not the nucleus is most dii-ectly concerned in the accumu- 

 lation and location of these degeneration granules and vacuoles. As 

 they accumulate about the centriole, the centrosphere gradually 

 expands and may attain a diameter equal to or even greater than the 

 nucleus, and thus the granules and vacuoles are pushed farther and 

 farther away. The exact cause of this enlargement is not known, but 

 the accumulation of granules, together with the increase in the amount 

 of cytoplasm, suggests that the activities of the centrosphere are in 

 some way increased during the degeneration of the cell. Experiments 

 have shown that undoubtedly some relation exists between the size 

 of the centrosphere and the accumulation of foodstuffs in the egg, and, 

 also, that it is larger in cells which are about to divide than in the 

 resting cells. The question as to whether the granules and vacuoles 

 have anything to do with its expansion now suggests itself. Such an 

 accumulation would naturally alter the relationship between the 

 centriole and the periphery and interfere with the metabolic balance, 

 since the metabolic activities centered in the centriole probably depend 

 upon a constant interchange of materials between the latter and the 

 periphery. 



Two papers have been published concerning the distribution and 

 formation of fat droplets. It has been shown by Dr. W. A. Mcintosh 

 that normally there is fat present in the epithelial cells of the stomach 

 and intestine of the cat which is not associated with the phenomenon 

 of fat absorption. This normal fat appears to vary, however, accord- 

 ing to some definite cycle of functional activity of the cells themselves, 

 at certain periods of which their lipoid content can be demonstrated 

 histologically, while at others this is not possible. The cats used by 

 this investigator were deprived of food for 24 to 28 hours, by which 

 time all evidence of fat absorption in the lacteals had disappeared. 

 Pieces were taken from various portions of the alimentary tract and, 

 by improved histological methods, droplets of fat were demonstrated 



