78 CARNEGIE INSTITUTION OF WASHINGTON. 



field of inquiry. In previous reports mention was made of observations 

 on the behavior of living cells toward certain differential stains, and an account 

 has been given of the studies of Professor W. H. Lewis on the reactions of 

 cells to the strong oxidizing reagent, potassium permanganate, which produces 

 phenomena resembling certain features of mitosis. The importance of the 

 presence of dextrose in the medium of tissue-cultures has been shown by 

 Mrs. M. R. Lewis, whose completed paper has just appeared. In continuation 

 of her work upon the chemical nature of cytoplasm, Mrs. Lewis has studied 

 the cells of small pieces of fundulus embryos explanted into hanging drops of 

 a suitable sea-water solution. By exposing the cells to iodine vapor she has 

 been able to demonstrate the presence of a substance that yields the char- 

 acteristic reactions of glycogen. When soluble starch was added to the 

 medium, even after an exposure of a number of days, it did not appear to be 

 utilized by the cells to store up glycogen. However, when dextrose was 

 eliminated from the medium, the glycogen-resembling substance was 

 decreased, although the presence of the latter could not in this way be en- 

 tirely inhibited. 



Reaction of Living Cells to Bacteria and Toxic Substances. 



The behavior of living cells when brought in contact with bacteria is of 

 considerable clinical interest. It will be remembered that Mrs. Lewis studied 

 the peculiar effect of the typhoid bacillus upon cells, which appears to be 

 characteristic for this organism. During the past year D. T. Smith, H. S. 

 Willis, and M. R. Lewis have followed the behavior of cultures of chick- 

 embryo tissue containing avian tubercle bacilli. They found that under 

 these conditions the bacilli were taken in by clasmatocytes, fibroblasts, white 

 blood-cells, endothelial cells, mesothelial cells, ectodermal cells, liver-cells, 

 renal epithelium in the tubules, and cells lining the bronchiales and alveoli of 

 the lungs. No microorganisms were observed in the red blood-cells, striated- 

 muscle cells, nerve-cells, or ciliated epithelial cells. It is of importance to 

 note that tubercle bacilli are taken into these cells precisely as are foreign 

 bodies. Entrance into the cell is dependent upon the consistency of the 

 cytoplasm, the composition of the foreign body, and also its position in rela- 

 tion to the surface of the cell. The only bacilli that are taken in by the cells 

 are those which come in contact with the cytoplasm throughout their entire 

 length. It is quite clear that the cell does not make any purposeful move- 

 ments towards taking in a foreign body, actively engulfing and ingesting it, 

 but rather the cell and the foreign body come together by chance and the 

 taking in of the latter is a physical phenomenon. The number of bacilli 

 taken in and the rapidity of the process appear to vary greatly with different 

 types of cells. In this series of experiments the clasmatocyte was the most 

 active; after that the giant cell, the non-granular white blood-cell, the granu- 

 lar white blood-cell, and the fibroblast, in the order named. When inside 

 the cell the bacillus moves back and forth in the cytoplasm in the manner 

 characteristic of included foreign bodies, and in course of time a vacuole 

 forms around it, the bacillus being eventually destroyed. 



A most interesting type of reaction on the part of living cells toward in- 

 jurious substances has been studied by Mr. J. L. Wilson. He has found that 

 the embryonic mesenchyme cell, when cultivated in weak solutions of copper 



