86 Natural History Bulletin. 



uals, kindly furnished by two packing houses, showed not a 

 a single case containing trichinae. 



An animal obtains trickince only by eating' the jiesh of some 

 other individual animal already infested. If a single trichinous 

 hog finds its way to our local slaughter yard, it will, when 

 killed, transmit trichinae to all other hogs that feed upon any 

 of the muscular parts thrown out with the refuse; these will 

 in turn transmit the parasites to their successors, and thus we 

 may have from any given yard a continuous supply of infected 

 animals. Rats, from their cannibal and omnivorous habits, 

 are particularly subject to inoculation with trichinae. Rats 

 often fall victims to the omnivorous appetite of the hog, and it 

 is quite certain that in many cases the rat is the direct cause 

 of infection among swine. In the case of the private family 

 hog that lives a solitary life in close quarters, rats are prob- 

 ablv always the immediate source of the parasites, when para- 

 sites are present. Our farm-fed hogs, living on corn and not 

 very closely confined, rarely have opportunity to indulge their 

 liking for flesh, and as a rule they are wholly exempt from 

 trichinae. The flesh of such animals may be purchased and 

 eaten with a sense of security from danger arising from mus- 

 cle parasites, that is well nigh absolute. 



Neglected cats, old individuals that have been compelled to 

 shift for themselves in cities and villages, are almost always 

 swarming with trichin£e. The young and the well-cared-for 

 individuals are usually exempt. 



To realize to the fullest extent the possibilities of a given 

 volume of muscular tissue to afford lodgment to trichinae the 

 observer must get an old slaughter-house rat, or at least one 

 from some place where rats congregate in large numbers and 

 feed on refuse animal tissues. Such a specimen was recently 

 brought to the laboratory. A rat was in demand for the pur- 

 pose of making observations on blood crystals; but the speci- 

 men procured turned out to be useless, the blood being scanty, 

 of a peculiar ropy consistency, and having the color of pow- 

 dered carmine instead of the rich scarlet color of normal 



