PROTOZOA 281 



meal) their numbers were rather in excess of those in the sheep. 

 Altogether, at two meals, I could not have swallowed less than 

 18,000 of these psorosperms. Consumers of beef, mutton, and 

 pork eat these bodies every day, but they take no harm because 

 the parasites in question are not true helminths. Fine healthy 

 beef has been returned to the butcher when it was as good as 

 any other meat in the market. I have examined various kinds 

 of meat, such as veal, pork, and mutton, but in none have I 

 found so great an abundance of psorosperms as in beef, which 

 was, notwithstanding, perfectly healthy and sound. I calculated 

 that in one instance a single ounce of the flesh contained upwards 

 of 2000 parasites. There is practically no limit to the extent 

 of this kind of parasitism, and there is no organ of the body in 

 which psorosperms may not be found. Moreover, the forms 

 they display are exceedingly various. Psorosperms have been 

 found by Siedamagrotzky in the muscles of the horse, and not 

 very long ago, through the help of Professors Simonds and Axe, 

 I had the opportunity to examine some peculiar worm-like 

 structures which occupied the mitral valve of a horse. To the 

 naked eye they looked like coiled nematodes, but I was soon con- 

 vinced that they formed a peculiar type of psorosperm. A 

 complete view of these bodies was a matter of great difficulty 

 owing to the delicate nature of their limiting membrane and to 

 the confusion of markings produced by the interlacing of the 

 fibres of the chordae tendinea. At length, by spreading a portion 

 of the membrane of the valve over a large glass slide, and 

 by allowing it to dry slowly, I found that the vermiform body 

 presented neither beginning nor end. The appearances were 

 curious and puzzling. The organism formed a flattened tube 

 or sac, almost uniform in width and variously twisted upon 

 itself. From the main tube there projected several hernia-like 

 secondary loops or branches, most of them presenting less 

 than half of the thickness of the former. These peculiarities, 

 however, can hardly be understood without reference to the 

 original illustrations. That these secondary coils were not of 

 the nature of hernial protrusions was evident, not alone from 

 the nature of their contents, but also from the fact that they 

 showed distinct anastomoses. In fact, the parasite was a simple 

 sac or bag with branches. 



On puncturing the main tube with a fine needle a small 

 quantity of tenacious creamy fluid made its escape. This, 

 under Ross's J-inch lens, resolved itself into a few excessively 



