LUNG FLUKES 



221 



tissues through which the parasite tunnels out its burrows and 



in which it deposits its eggs (Fig. 70). These excavations in the 



lung connect with the bronchial tubes, through which the blood, 



parasite eggs and other products are voided, thus causing the 



characteristic blood-spitting. The 



expectorations, resembling those 



of pneumonia, are of a peculiar 



brownish red color, due in part 



to the blood corpuscles present 



and in part to the dark brown 



fluke eggs, which are often very 



abundant. 



Occasionally the lung fluke bur- 



rows in other organs and glands 



of the body, such as the liver, 



spleen, muscles, intestine and 



brain. Musgrave found in the Philippines that sometimes many 



parts of the body are infested at once, and in one case he found 



over a hundred mature parasites in a muscular abscess. When 



they burrow in the brain they cause epileptic fits and usually in 



time cause death. 



The eggs of the lung fluke (Fig. 71 A) when immersed in fresh 



water for several weeks develop 

 within themselves typical ciliated 

 embryos or miracidia (Fig. 7 IB). 

 The latter burst away the little 

 cap at the end of the egg and 

 emerge as free-living animals. 

 FIG. 71. A, freshly passed egg Nakagawa has recently shown 



of lung fluke; B, egg of lung fluke that if these miracidia are placed 

 fdPbry0 - ' in water with certain species of 



FIG. 70. Eggs of lung fluke in 

 contents of cyst in lung of hog. X 

 about 50. (After Stiles and Hassall.) 



snails, particularly Melania liber- 



tina, the miracidia swarm about the snails and burrow into them, 

 shedding their cilia as they go. The entire cycle of development 

 in the snail has not been worked out but it is probably very similar 

 to that of Schistosoma. Sporocysts of various sizes occur in the 

 liver and other tissues of the snail, and it is probable that these 

 produce the cercariae directly. 



Nakagawa discovered the encysted cercariae of this species, 

 proved to be such by experimental infection of animals, in three 



