500 
F. S. BILLING8. 
means or ways by which further migration takes place. Some 
authorities, and among them the most eminent, as Leuckart, 
Furstenberg, Gerlach, favor the view that the parasites proceed 
by the way of the mesenterium and connective tissue tracts over 
the system, and penetrate the sarcolemrna, or connective tissue 
membrane of the muscle fibres, to lodge in the substance-plasma 
of the same. Here the parasite develops a capsule or bed, of a 
finely granulous character, for itself, the sarcous elements of the 
fibres becoming wasted or used up, and the striation of the fibres 
lost, so far as the capsule of the parasite extends. The sacolemma 
of the muscle fibre forms a thickened, secondary capsule around 
the parasite. 
Another view, the possibility of which is conceded by the 
above named authorities, to a minor degree, is that the parasites 
gain access to the circulation, and are transported over the system 
by the moving fluid, boring the smaller vessels at convenience, 
and in this means gaining access to the muscles. An enthusiastic 
defender of this theory is Dr. Thudicum, an English observer. 
Were this latter the principal path of dispersion, however, we 
ought to be able to find numerous examples of the parasite in the 
circulating blood of living animals which have been subjected to 
feeding experiments. This has not been the case, however. 
Thus it is evident that the host or consumer of trichinous flesh 
provides the means for its own infection. 
While this is in general the manner by which infection takes 
place, it by no means excludes the possibility of the infection of 
an animal taking place by intestinal trichnae which have passed 
from an already infected organism with its faeces. In this way 
an infected swine may infect others, or in fact give occasion to a 
secondary infection of itself, by rooting the manure of its pen. 
In the same way swine may become infected from infected men, 
where, as is too often the case, the out-houses for the family are 
placed over the piggery, or lead into it; or where the contents of 
the same are thrown into the piggery for the swine to work over. 
Thus we see the cycle of infection may frequently con¬ 
tinue from swine to man, and man to swine. The trichinae may 
be assumed to be regular cosmopolitans. They have been discov- 
