PENTASTOMA CONSTEICTUM. 401 



slimy nasal mucus secures this attachment, especially when it has 

 become dry by exposure to the air. On reaching the stomach the 

 embryos will escape from the egg-coverings and bore their way 

 directly to the liver and other viscera, in which organs they 

 become encysted and undergo the pupal transformation. Even- 

 tually they may acquire a length of two to two and a half lines, 

 and at this stage they constitute the true larval form (Pentastoma 

 denticulatum) . After a while, the capsules enclosing them undergo 

 calcareous degeneration, the parasite itself subsequently perishing. 

 In the case of dogs, it is easy to perceive that when they are en- 

 gaged in devouring the flesh of herbivora, the liberated larv^ will 

 often come in direct contact with their noses. In this way, a few 

 contractions of the body of the worm, aided by its foot-claws and 

 integumentary denticles, wiU readily secure its entrance into the 

 nasal frontal cavities. For our own security, therefore, we should 

 avoid close contact with all dogs which frequent butchers' shops 

 and knackeries, and especially, also, be sure that our market-garden 

 fruit and vegetables be duly washed and cleaned before they are 

 brought to table. 



2. Pentastoma oonstrictum. 



P. constrictum, Von Siebold ; Bilharz ; Leuckart. 

 Linguatula constricta, ? Kiichenmeister. 

 Nematoideum hominis, Pruner ; Diesiug. 



As already hinted, by the quotation I have given above, from 

 Frerichs, there is good ground for believing that at least two 

 species of Pentastoma infest the human body. This second species, 

 however, is at present only known to us in an immature condition, 

 unless, indeed, as is by no means improbable, we are acquainted 

 with the adult worm under some other name. It was first dis- 

 covered 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 girafie. Bilharz has 



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