55S 
A. 0. ZWICK. 
the seat of election for the attacks of pathogenic micro-organ¬ 
isms, because I take it, the circulatory conditions, much resemb¬ 
ling those of the lungs, are favorable to such processes. 
In 1626 Harvey demonstrated the circulation of the blood in 
his work, De Motu Cordis et Sanguinis. That the blood passes 
from the arteries into the veins is a necessary corollary of this 
doctrine, but the mode of passage through the capillaries was not 
ascertained until discovered by Malpighi in 1661. These are 
most commonly arranged in a network of nearly uniform size 
in a given part, though not strictly equal. Speaking generally, 
their average size may be stated to range from 1-3,500 to 1-2,000 
of an inch. Weber describes some as small as 1-4,500 of an inch, 
and Henle even smaller, some so small, at least on post-mortem 
examination, as really not to permit a blood-corpuscle to pass! 
Now, the smallest of them are in the lung, where the capil¬ 
lary network is very close, as it also is in glands and secreting 
structures, as well as in the gray part of the brain and spinal 
cord. And in infants and young persons the tissues are com¬ 
paratively more vascular than in later and adult life, i.e., vascu¬ 
larity goes hand in hand with tubercular death rate! We need 
only allude to the filtering function of the lung to make our mean¬ 
ing plain and understand the fact. Right here, however, the ques¬ 
tion might be asked, why, then, does not syphilis, in the self-same 
manner, as is claimed by this paper, for tuberculosis reach the 
lung and localize there ? Perhaps this slide shows the reason, at 
least in so far as it shows a distinctive difference in the behavior 
of the spirocheta pallida and the tubercle germ towards the blood 
corpuscles; the spirocheta pallida does not enter the blood cor¬ 
puscles, hence is not by them conveyed to distant parts. Such 
opposite behavior is further illustrated by the different behavior 
of syphilis and tuberculosis in other respects. The same argu¬ 
ment holds good with regard to, for instance, the germ of the 
sleeping sickness. Going farther, the explanation of the differ¬ 
ence in the behavior of the two germs, and others, in fact, for 
that matter, may with justice and probability be sought in Ehr¬ 
lich’s side-chain theory. 
