316 The American Naturalist. - [Apri 
THE ACTION OF LEUCOCYTES TOWARD 
FOREIGN SUBSTANCES: 
Epiru J. CLAYPOLE, M. S. 
Among the many problems that yet await solution at the 
hands of the physiologist and histologist, those relating to the 
disappearance of so many leucocytes or white blood corpuscles 
from the animal body have long afforded a fruitful field for 
work. Under what conditions and by what means they are 
destroyed is as yet but partly known, and different theories are 
advanced as to the most probable method of this destruction. 
‘The constant relation, normally, that exists between the num- 
bers of the white and red cells of the blood, in spite of the 
steady supply of white cells that is poured into the blood from 
the lymphatics, establishes the fact that somewhere there is as 
steady a drain on the numbers. 
The nature of leucocytes as entities in the economy of the 
animal body is of especial importance in consideration of the 
second point and a careful study of these cells in a living con- 
dition helps one to realize their activities and powers. e 
ability of these cells to take up foreign substances by virtue of 
their amoeboid movement is very significant to the physiologist 
especially from a pathological standpoint. The great Russian 
morphologist, Metschnikoff, has based his phagocyte doctrine 
on the peculiarity given to these cells by the exercise of this 
power, giving to them in consequence an additional and aid 
portant duty. They form, as it were, a guardian army 12 ls 
animal body, ever alert and watchful for the invading enemy. 
A constant warfare is being waged between these leucocytes an 
all foreign material, organie or inorganic, that enters the 
system. By the process of ingestion the immediate influence 
* This paper contains part of the results of an investigation carried on in the yas 
logical Laboratory of Cornell University during last year. I wish to BRT rs 
appreciation of the abundant material and facilities which were so generously ip 
my disposal. The whole paper afterwards received the first prize offered by 
American Microscopical Society for original work in animal Histology. 
