ARACHN1DA 263 



As the full-grown parasite occupies the nasal chambers of the 

 dog, it is clear that the act of sneezing will be liable to transport 

 the eggs and their contained embryos to the face and other ex- 

 posed parts of persons who fondle dogs. In this way the germs 

 will readily gain access to the human mouth. Ordinarily, the 

 germs are introduced into the human stomach with uncooked 

 vegetable food and fruits, to which they adhere after expulsion 

 from the animal's nostrils. The slimy nasal mucus secures 

 this attachment, especially when it has become dry by exposure 

 to the air. On reaching the stomach the embryos escape the 

 egg-coverings and bore their way directly to the liver and 

 other viscera, in which organs they becomes encysted and 

 undergo the pupal transformation. Eventually they acquire a 

 length of 2 to 2\ lines (P. denticulatum) . After a while the 

 capsules enclosing the larvse undergo calcareous degeneration, 

 the parasite perishing. 



In the case of dogs it is easy to perceive that when the 

 animals are engaged in devouring the flesh of herbivora, the 

 liberated larvas will often come in contact with their noses. In 

 this way contraction of the body, aided by the integumentary 

 denticles, will secure their entrance into the nasal cavities. For 

 our own security, therefore, we should avoid contact with dogs 

 which frequent butchers' shops and knackeries, and be sure that 

 our market-garden fruits and vegetables are carefully washed 

 before they are brought to table. 



Pentastoma constrictum, Yon Siebold. This parasite is at. 

 present only known to us in the immature condition; unless, 

 indeed, as is by no means improbable, the adult worm has been 

 described under some other name. It was first discovered by 

 Pruner on two occasions in negroes, and he also subsequently 

 found two specimens of the worm preserved in the Pathological 

 Museum at Bologna, which had been removed from the human 

 liver. Pruner also found it in the giraffe. Bilharz afterwards 

 frequently detected* it in the livers of negroes at Cairo. It 

 differs from the larval form of P. tcenioides in not possessing 

 integumentary spines ; moreover, it is a much larger parasite. 

 The cephalothorax is furnished with four foot-claws, and the 

 elongated abdomen displays twenty-three rings placed at tole- 

 rably regular intervals. The anterior part of the animal is 

 obtusely rounded off, the caudal end being conical. The worm 

 usually attains a length of rather more than half an inch, whilst 

 the breadth scarcely exceeds a line. 



