PARASITIC DISEASE OP LUNGS. 365 



degeneration ensue. The eggs are of an oval shape. They 

 are at first transparent, but in all those that are fecundated 

 the yolk cleaves, and, by progressive subdivision of cells 

 formed out of the yolk, a cellular mass is formed, which 

 assumes an elongated and coiled appearance, and presents 

 the external form and internal organisation of the strongylus 

 filaria. The parasite, coiled on itself and alive in the cell, 

 moves about, and at last becomes free and grows to its full 

 size, passing out of the tissue of the lung into the air passages, 

 whence it is coughed out and often deposited on grass and 

 other substances likely to be eaten by the sheep. How it 

 attains the lungs to deposit its eggs is involved in mystery, 

 perhaps by directly piercing the tissues from the stomach 

 to the lungs; though, from the eggs being universally dis- 

 seminated over the lung, we might be led to conjecture that 

 the ova are introduced into the circulation and stopped in the 

 pulmonary capillaries, where they produce irritation, and the 

 deposit, before described, accumulates around. 



The strongylus filaria is a worm from one to two and a 

 half inches in length, the male smaller than the female and 

 yellowish, whereas the latter is white. The body is of uni- 

 form size, but tapered at the extreme ends. Anteriorly is 

 the head, short, stumpy, and matted, not tuberculated as that 

 of other strongyli, but rather angular. From the mouth 

 extends a short oesophagus into a short but elongated stomach, 

 and from this the straight intestine extends back nearly to 

 the extreme end of the tail, a little anteriorly to which is the 

 anus. In the male an undivided circular aliform expansion, 

 obliquely situated to the line of the body, surrounds a space 

 in which the penis is observed. The tail of the female is 

 pointed, the vulva situated near the anus, and from the vulva 

 extend the oviducts full of eggs, and containing also live 

 young. 



