70 CARNEGIE INSTITUTION OF WASHINGTON. 



with which the ingested organism is destroyed is the reason why this phe- 

 nomenon is so rarely observed in the animal body. Owing to the favorable 

 conditions under which the process of phagocytosis can be studied in inocu- 

 lated cultures of connective-tissue cells, Mrs. Lewis was able to observe each 

 step, a very complete account of which is given in her publication. I shall 

 have occasion to return to the subject of phagocytosis in connection with the 

 work of Dr. Cunningham. 



Janus-Green Granules in Visual Cells. 

 The living visual cells of the embryo and adult fowl have been studied by 

 Mrs. M. R. Lewis in respect to their reaction to janus green, and it was found 

 that, although certain granules reacted to this stain, it did not color those 

 structures which, in fixed material, appear to be mitochondria. In newly 

 hatched and adult specimens, the j anus-green granules are assembled in a 

 mass just proximal to the fat-globule and correspond to the so-called elhpsoid 

 of fixed and stained material. There are also a few scattered granules around 

 the nucleus. In the visual cells of progressively younger embryos they are 

 less and less closely aggregated, until in embryos of 15 days' incubation 

 one finds them mostly as filaments arranged axially throughout the elongated 

 portion of the cell. At this time there are also more granules around the 

 nucleus. In embryos of 11 days' incubation the janus-green granules are 

 largely segregated in the protoplasmic bud. In studying these cells, Mrs. 

 Lewis found that their filamentous outer segment exhibits changes that are 

 strikingly like those seen in the sarcostyles of insect wing-muscle. They 

 contract, become cross-striated and segmented, or are broken up into disks. 



Giant Centrospheres in Xanthomatous Tumors. 

 In his study of the giant centrosphere that is found in degenerating tissue- 

 cultures, Dr. Lewis pointed out that it is identical with the cancer-cell inclu- 

 sion known by the name of Plimmer body, and he suggested that these bodies 

 might be found in pathological conditions other than cancer. This prediction 

 has been fulfilled in part by the discovery of the giant centrosphere in xantho- 

 matous tumors. Dr. D. T. Smith studied 17 specimens of this rare tumor 

 and found that giant centrospheres were present in the pigment-containing 

 cells of 9 of them. Where there was no degeneration they appeared to be 

 absent, and the whole evidence now points to their being related to a dis- 

 turbance in the metabolism of the cell. 



Migratory Cells in Tissue-Cultures op Spleen. 

 When minute pieces of the spleen from young chick embryos (7 to 9 days) 

 are placed in a suitable culture medium, there ensues a profuse growth of 

 mesenchymal cells and frequently of broad sheets of mesothelium. Some 

 blood-cells also migrate out. In growths from older embryos, mesenchymal 

 and mesothelial cells are seldom seen, whereas blood-cells are present in great 

 numbers and varieties. On account of the particular interest that is now 

 associated with the study of living blood-cells, Mr. David Rioch has taken 

 advantage of the new method of approach offered by these spleen cultures to 

 observe the structure and behavior of blood-cells under these conditions, 

 particularly their locomotion, phagocytosis, and reaction to dyes. His 

 observations upon the phagocytic power of the blood-cells were carried out, 

 for the greater part with melanin granules, by placing teased pieces of the 



