1901 - 2 .] Experimental Observations on Leucolysis. 295 
most marked necrobiotic changes, but also the greatest variation in 
their amount. In cases showing leucocytosis the young forms 
suffer most. We find leucolysis much more marked in cases of 
malignant cachexia without increase in the number of white cells 
than in cases showing leucocytosis. Again, in severe pneumonia 
cases the amount of necrobiotic change was always greater when 
the total number of leucocytes was comparatively low. In 
scarlatina with marked leucocytosis the changes are but slight. 
The explanation seems to be that a high birth-rate keeps the 
leucocyte population fairly healthy, in spite of infant mortality and 
adverse circumstances. There are several directions in which our 
observations might be extended, but meanwhile we would state the 
following conclusions : 
1. Necrobiotic changes occur in the , circulating leucocytes in 
health. 
2. These changes are much more evident in conditions of 
impaired nutrition and toxsemia, notably in cancerous cachexia. 
3. In toxic conditions usually associated with leucocytosis the 
extent of the necrobiotic changes in the white cells varies in inverse 
ratio to the number of leucocytes in the circulating blood. 
4. These necrobiotic changes can be rapidly induced “ in vitro ” 
by the action of certain organisms or their products. 
The rapidity and extent of the changes depend on 
(a) The kind of organism. 
(b) The virulence of the culture. 
(c) The number of organisms employed. 
We wish to express our indebtedness to Dr James for kindly 
placing his cases at our disposal, and to the Superintendent of the 
Royal College of Physicians’ Laboratory for affording us facilities 
in connection with the bacteriological part of the work. 
[References. 
