90 THE INTEKNAL PAEASITES OF 



eastern countries. Dr. Lewis's recent discovery of similar 

 parasites in the human body in India has called forth 

 the energies of many microscopic observers ; and Mr. 

 Swinhoe informs me that Dr. Little, of Shanghai, is 

 especially engaged in studying the structure and develop- 

 ment of the cruel thread worm. I may here add, as a 

 result of my own observations, that the tail of the male 

 Filaria immitis is furnished with an elegant and trans- 

 parent membrane or hood, which is supported upon eight 

 oval glandular papilliform rays, four on each side. These 

 are arranged in pairs, the upper two being the largest, 

 whilst the terminal pair are the smallest, and lie a little 

 behind the point where the two spicules emerge. Under 

 the half-inch objective glass they present a beaded and 

 highly attractive appearance. 



It seems somewhat strange that neither in the dog nor 

 in the human bearer do the microscopic filarise appear 

 capable of setting up bad symptoms. Thus, Messrs. 

 Grube and Delafond (who found European dogs enter- 

 taining upwards of 200,000 of these minute worms at a 

 time) state that in no case did the infested animals 

 appear to suffer inconvenience. In like manner, as Dr. 

 Lewis tells us, people in India go about with thousands 

 of living embryonic nematode parasites in their blood, 

 and yet do not betray any evidences of suffering. 



Though of comparatively rare occurrence in the dog, 

 there is a large lumbricoid worm which deserves a 

 separate notice, however brief. This is the giant strongle 

 (Estrongylus gig as) which infests the kidneys of various 

 animals, proving especially destructive to the North 

 American mink (Fig. 18). The males rarely exceed ten 

 inches in length ; but the females have been known to 

 exceed a yard in measurement from head to tail, whilst 



