ACAEINA OR MITES. 137 



the dog along with mucus. The ova are eaten by sheep, oxen, 

 rabbits, and other herbivora, when the embryos (b) are released 

 in the intestines. By means of the median rod and curved 

 hooks this minute embryo bores through the intestines and gets 

 to the liver, lungs, and mesenteric glands, where encystment 

 takes place. It here soon becomes converted into a simple 

 rolled up pupa (c), with no legs, hooks, or bristles. By a 

 repeated series of moults a second larval form is reached (d), 

 and which is said to last for seven months, by which time it 

 has grown to the length of one-third of an inch. In this stage 

 it was taken to be a distinct species called L. denticulatum. 

 Numerous spiny rows are present on the skin. They fall from 

 the organs they are in, to the body cavity and pleural spaces, 

 and the majority die. Some, however, encyst themselves in 

 fresh parts of their host, and even enter the air-tubes, and are 

 so passed out of the host ; or they may possibly enter the nasal 

 cavities of the herbivora they live in, during their early life. 

 More generally they reach maturity in the nasal cavities of the 

 carnivora which happen to eat the flesh of infected herbivor- 

 ous animals. In this last host they become sexual adults (e), 

 with a smooth ringed skin, and are vermiform in shape. The 

 males wander about the pharynx, larynx, and nasal cavities, 

 and fertilise the stagnant females, which take up their abode 

 between the turbinated bones and other nasal spaces. One 

 female, according to Leuqkart, may produce 500,000 eggs. 

 They sometimes occasion loss, but are not very prevalent in 

 Britain. Dogs should not be given the fresh viscera of sheep, 

 oxen, &c., and then there would be no chance of any such 

 disease appearing in a serious form. 



