140 BOARD OF AGRICULTURE. 



mant and enclosed in cysts, in which they pass a sort of 

 pupa state. During this period of their life, the skin is cast 

 several times, and the appearance changes at each moult^ un- 

 til they attain the next period of their life, when they 

 again become active ; this is the state described as Petastoma 

 denticlatum. These larvee are long-oval, broadest anterior- 

 ly, and covered with numerous rows of transverse tooth-like 

 spinules. They have two pairs of sharp, curved claws, which 

 are situated near the mouth and placed obliquely, diverging 

 from the median line of the body, and directed downward. 

 Each claw has a sort of hood or capsule, into which it can be 

 retracted. If dogs feed on the liver or other viscera of animals 

 containing these larvse, they come in contact with, and man- 

 age to enter the nose, working their way up by means of the 

 motions of the body, aided by their spines and claws. In 

 this situation they gradually become mature. 



In the human body the larval form is quite frequent, es- 

 pecially in some parts of Europe ; but there is little known 

 concerning the effects that it produces. When in small num- 

 bers, it probably causes very little disturbance, but if in large 

 numbers, in the liver and lungs, it would no doubt produce 

 serious disease, as does another species (P. constrictuni) , 

 which is very common in Egypt, living in the same way en- 

 cysted in the liver and lungs. The latter, when in consider- 

 able numbers, frequently proves fatal. 



As a means of prevention, dogs that show symptoms of 

 the parasites in the nose, should be treated to a solution of 

 carbolic acid, thrown up the nostrils by a small syringe. 

 Feeding dogs with the offal of slaughter houses, or with un- 

 cooked livers, etc., should be avoided, both on account of this 

 and the other dangerous parasites that they get in this way, 

 (see Tcenia echinococcus, p. 202, T. marginata, p. 192, T. 

 coenwus, p. 196, and Trichina spiralis, p. 222). Too much 

 familiarity, especially of children, with dogs is always liable 

 to result in the transfer of these and other parasites to the 

 human body. 



