92 CARNEGIE INSTITUTION OF WASHINGTON. 



and migration was no more abundant than in hypotonic media. Both 

 migratory and reticular growths were much the same as normal, and 

 when stained the mitochondria and neutral-red granules were arranged 

 as in the controls. These three hypertonic solutions show a definite 

 gradation in their effects on the processes of the fibroblast. In Locke- 

 Lewis solution containing L8 per cent sodium chloride the processes 

 rapidly contract, become thread-like, and are withdrawn, and the cell 

 soon dies. In the 1.5 per cent solution the processes frequently become 

 thread-like, but some of the cells recover. In the 1.2 per cent solution 

 the processes form and continue to move as long as the cell is alive. 



Occasionally an interesting effect was observed on the part of the tis- 

 sue to adapt itself to the new medium. Transparent, balloon-like 

 structures of various sizes would arise out of the explant and lie along 

 its margins, enlarging as if by imbibition of fluid from the tissue. Simi- 

 larly, granular hills also appeared along the edges of the cultures. These 

 were stable and lasted as long as the cultures were kept, though occa- 

 sionally they broke open and poured fine granules into the surrounding 

 medium. 



Testing the effect of an active oxidizing reagent upon tissue cultures, 

 Dr. Lewis finds that cultures treated with a weak solution of potassium 

 permanganate (1/20,000 to 1/80,000) are usually killed in from 3 to 30 

 minutes. An interesting series of reactions takes place in the cyto- 

 plasm and nucleus of the dying cell. The nucleus is usually the first 

 affected; it becomes mottled, more refractive, a membrane appears, 

 and finally clear vacuoles are given off with a corresponding shrinkage 

 in the size of the nucleus. Thus, pycnotic nuclei result which stain 

 intensely in fixed material. Dr. Lewis points out that these changes 

 have one of the essentials of mitosis; that is, a separation out of the nu- 

 clear sap and a segregation of the nuclear material into a chromosome- 

 like mass. Shortly after the nuclear changes begin the mitochondria 

 become irregular; they often break up into shorter lengths and later 

 swell up into vesicles. Mitochondria stained with Janus black lose 

 their color. In cells fixed while these changes are in progress the endo- 

 plasm becomes concentrated into a dense, deeply staining mass, either 

 opposite to or on the same side of the nucleus as the centrosphere, the 

 latter not being affected. As the cell dies the granules and vacuoles, 

 if already stained with neutral red, lose their color. 



Important observations have been made by M. R. Lewis concerning 

 the effect of bacteria, especially of Bacillus typhosus, upon growing 

 cells. Pieces of the intestine from chick embryos of 7 to 9 days' incu- 

 bation were transplanted in Locke-Lewis solution, and after a normal, 

 healthy growth was assured the cultures were inoculated with typhoid 

 bacillus. This was done by touching a platinum wire against a growth 

 of the organisms and then inserting it into the hanging drop. This 

 caused rapid degeneration of the cells and death usually followed within 



