TEACHEARIA. 795 



of various animals, especially ruminants, as well as in man 

 himself. The larva, which is commonly described as the Penta- 

 stoma denticulahim, usually measures about one-fifth of an inch 

 in length ; but the adult males are three-quarters of an inch long, 

 whilst the females occasionally measure as much as four inches 

 from head to tail. 



The history of the development of these curious parasites is 

 somewhat remarkable and of great practical interest. The female 

 discharges her eggs v/hilst within the nose of the dog. From 

 the nasal passages the eggs are constantly discharged by sneezing 

 and otherwise. They are thus scattered by the canine host in 

 all directions, and by the drying of the slime they adhere very 

 readily to vegetable and other matter. Afterwards, on being 

 transferred to the stomach of ruminating and other animals, their 

 embryonic contents are set free by the dissolution of the shells- 

 The embryos, which are furnished with two pairs of claws, then 

 bore their way into the liver and other viscera. They next be- 

 come encysted and change their skins. After a time, the larvse 

 are set free, but their wanderings are ordinarily of no avail, 

 unless portions of the infested animal are brought in contact 

 with the nose of the ultimate bearer. In the case of the dog, 

 this commonly happens when the animal is engaged in devouring 

 portions of fresh viscera carelessly flung to it. The larvije are 

 thus brought in contact with the dog's nose, and then, by means 

 of the hooks and spines with which they are armed, the young 

 pentastomes readily adhere to the nose, and in a short while 

 crawl up the nasal passages, where they rapidly acquire sexual 

 maturity. It is not so clear how they make their way into the 

 nasal cavities of the sheep and horse ; but in all probability some 

 larva escape from the bodies of their intermediary bearers into 

 open pastures, and thence into the nasal organs whilst these 

 animals are grazing. Dogs that frequent knackeries and 

 slaughter-houses are particularly liable to become infested by 

 the adult parasite. Such larvae as do not succeed in escaping 

 their cysts perish by calcareous degeneration. 



To the veterinarian these facts of development are chieily 

 important as explaining how dogs contract the parasite ; and 

 although instances of suffering from these entozoa may not be 

 common, there is every reason to believe that examples of the 

 kind are not unfrequently overlooked. It is certain that dogs 



