812 



PARASITIC DISEASES. 



of at least seven-tenths. They have a digestive tube divided 

 into numerous compartments or sacculated; a mouth un- 

 armed." 



Professor Dick's own statements, as communicated by Dr. 

 Knox, are particularly interesting. He says — " I have found 

 these worms in several horses, and at different stages of their 

 growth, from the size of a pin-point to that of an inch and a 

 half in length, and in two instances in the blood-vessels. 



" They seem almost always to produce a bad form of diarrhoea, 

 and seem to depend on the food or situation in which the animal 

 has been previously kept. The horses I have found affected 

 with these have always been running out previous to their be- 

 coming iU." 



During the spring of 1874 I had again the opportunity of 

 studying the disease caused by this parasite, or rather parasites, 

 for I am of opinion that there were at least two kinds present 

 in the subjects examined by me, some being embedded in the 

 intestinal walls and others in the intestinal canal, the latter 

 being a reddish-looking worm, very similar to a small earth- 

 worm, from two to three inches in length. Those embedded in 

 the intestinal walls, as well as the appearance of the intestines^ 

 are delineated in the following woodcuts. 



Fig. 48. 



Fig. 49. 



Microscopic appearance of StrongyTus tetracanthus embedded in 

 mucous membrane of Iceland pony, described in the text. These 

 worms were of a bright red colour. (About 100 diam.) 



