CIRCULATORY ORGANS 



253 



This parasite is not visible to the unaided eye. Microscopically, it is 

 found to be similar in shape to an oat grain and has four pairs of 

 short legs. The life cycle of this parasite is practically the same as 



Fig. 61. Convenient trough for vaccinating swine. 



of the Sarcoptes scabiei, var. suis, except that the ova are deposited 

 in a pustule in the hair follicles and sebaceous glands instead of in 

 intradermal galleries. 



