336 PARASITIC DISEASES. 



tal people, and in such numbers that on opening the intestine 

 it appears covered with leeches. 



So far as my own inquiries extend as to parasites in the 

 lower animals, none kill by merely draining the system of 

 blood. I shall refer elsewhere to this supposed action of 

 distoma haepaticum. 



Parasites are living and moving bodies, and in their peri- 

 grinations through the system, or in their movements in a 

 part in which they are lodged, they induce great derange- 

 ment, and may kill. I have witnessed this in my experi- 

 ments with coenuri, and when many germs are introduced 

 into the system of pigs and calves, &c., for the development 

 of hydatid disease, deaths are frequent when the embryos 

 bore through the tissues. In the pig death occurs from the 

 piercing of the intestine by echynorhyncus gigas, &c. 



Leuckart refers particularly to the injurious effects of the 

 movements of parasites. They induce an irritation which is 

 followed by congestion and inflammation varying in intensity 

 according to the number of parasites, and the rapidity of 

 their movements. He adds that " the most striking example 

 of the truth of these statements is afforded by the trichinae, 

 which, on their passage into the intestinal canal, induce a 

 malignant enteritis with the production of false membranes, 

 and lead to appearances which have a great resemblance to 

 those of typhus. This happens, at all events, when the num- 

 ber of imported parasites is great, amounting, perhaps, to 

 upwards of 100,000, as is not rarely found after the eating of 

 trichinous meat. I have seen a corpse in which half-an- 

 ounce of flesh contained about 300,000 trichinae. In other 

 cases the direct results of the parasitism are milder, but 

 always under the form of a congestive state and catarrhal 

 affection." 



Not unfrequently parasites induce indirectly a derange- 



