912 CYCLOPiCDIA OF LIVE STOCK AND COMPLETE STOCK DOCTOR. 



ranging from 48 degrees to 60 degrees F. forty-one days are required 

 for the eggs to hatch. The hfe history and habits of the worm have been 

 studied by Conradi and Barnett. 



Upon hatching, the young hook worms are very minute, but can easily 

 be seen with the aid of a hand lens when crawling on the glass walls of 

 the breeding' jars. They have a tendency to congregate, and these clusters 

 can be easily recognized with the unaided eye. In this stage, as well as 

 in the egg stage, they are very susceptible to heat or cold, being easily 

 killed. Drought is also fatal, the worms dying in a few minutes. They 

 feed on the fecal matter about them. In the second stage they are but 

 slightly hardier. After several days the body wall becomes thicker and 

 more rigid, and soon they pass to the final larval stage. 



The larvae that were hatched from eggs, gathered from fresh feces on 

 February 26, and hatched February 28, had mostly passed to the final 

 larval stage on March 15. ' In this stage they are protected by a resistant 

 covering called ''sheath." Worms kept in the laboratory during January 

 and February, the temperature varying from 48 to 60 degrees F., passed 

 to the final larval stage in forty-one days. While active they were able 

 to continue feeding through the aperture in the front end of the sheath. 

 They move up and down on any near-by moist object, whether it is earth, 

 grass, leaves, or weeds. They finally become quiescent in some elevated 

 position, discontinue feeding, and are then greatly resistant to heat, cold, 

 and drought. This habit of rising appears to be advantageous, as we be- 

 'lieve, the principal method of host infestation is through the mouth. 



That part of life history from egg to larval stage is very probably com- 

 pleted in a few days during the warm weather of summer. 



The eggs and young worms require moisture. It seems quite probable 

 that little development takes place in feces dropped on a hill during the 

 drought of summer. There is said to be little danger from infestation in 

 running water. 



At present the outlook for a cure for this disease is not very encouraging. 

 Thymol has given good results in the treatment of the disease in man, and 

 has been recommended by some authorities for the disease in cattle and 

 sheep, but we believe it is far from being a specific. Certainly, in the 

 case above referred to, with a dose of 150 grains, it could not be noticed 

 that the worms had been in the legist affected three days later. How- 

 ever, further experiments with this drug will be made as opportunity pre- 

 sents itself. Even if drugs such as thymol were effective in expelling the 

 worms, the animal, if still pasturing on infested land, would continue to 

 reinfcst itself, so that the problem resolves itself into a question of pre- 

 vention rather than treatment, the outlook for which is more encouraging. 



What to do. — When it is remembered that the disease occurs chiefly, or 

 altogether, on low, wet lands, and that in dry seasons it is less severe, it 

 would appear that much could be done by avoiding such places as pastures 



