108 CARNEGIE INSTITUTION OF WASHINGTON. 



The experimental side of cytological investigation is represented 

 in this year's work by two papers on mitochondria (B. Strongman and 

 W. J. M. Scott), a paper on the development of connective-tissue 

 fibers in tissue cultures (Margaret R. Lewis), and a number of others 

 on the subject of vital dyes (MackUn, Shipley and Macklin, Wislocki, 

 Shipley, and Cunningham). 



Miss Strongman endeavored to ascertain if changes occur in the 

 mitochondria of nerve-cells after prolonged nervous activity. She used 

 white mice and made them swim until they were exhausted. No 

 definite changes could be detected, either in the number or the form 

 of these bodies. 



Mr. Scott studied the effects of phosphorous poisoning on mito- 

 chondria in the pancreas of white mice. It appears that mitochondria 

 are the first constituents of the acinus cell of the pancreas to show path- 

 ological changes in phosphorous poisoning. They lose their filamentous 

 form, become shorter and thicker, and the bleb-like swelhngs so 

 characteristic of the normal pancreas completely disappear. Then 

 follows the stage of agglutination, in which the mitochondria collect 

 in large clumps and fuse to form droplets possessing the characteristic 

 properties of Upoids. 



Mrs. Lewis summarizes her studies on the development of connective- 

 tissue fibers as follows: The connective- tissue fibrils begin to develop 

 in the subcutaneous tissue of chick embryos of from 9 to 10 days' 

 incubation, and appear as well-developed fibers in the subcutaneous 

 tissue of a 12-day chick embryo. The cut fibers which are present 

 in the explanted piece of subcutaneous tissue from an 11 to 15 day 

 chick embryo do not grow either in length or bulk in the tissue cultures. 

 The fibrils develop as dehcate fines of the exoplasm of the cell, and the 

 bundles later pass over or through the exoplasm of several cells as a 

 definite fiber. There is evidence that the fibrils are formed by a secre- 

 tory activity of the grains de segregation (vacuoles) of the connective 

 tissue. The fibrils of the epithelial cells of the amnion appear to form 

 in the same manner as those of the subcutaneous tissue — i. e., from the 

 exoplasm of the cell, and not from the fusion of the walls of the vacuoles. 



Dr. C. C. Macklin used madder to feed animals which possessed 

 calcium-salt concrements of different kinds, the idea being to find out 

 whether the processes underlying the formation of normal bone and of 

 pathological calcific deposits are, as claimed, really similar if not iden- 

 tical. In experimental calcification of the kidney, obtained through 

 unilateral figation of the renal vessels, and under the intermittent 

 influence of madder feeding, the calcific deposits were found stained. 

 From these results it is befieved that all pathological calcific deposits 

 in process of formation will stain with madder. 



Doctors Shipley and MackUn studied the bones of young animals 

 after injections of trypan blue into the peritoneal cavity. They found 



