STRONG YLUS TETRACANTHUS. 811 



Eabe used picrate of potash in the small dose of 012 grms., 

 or about 2 grains per day for three days, and was successful in 

 his treatment. The picrate of potash was given in thick linseed 

 mucilage. 



The doses of picrate of potash as given by Zurn are — 

 For a lamb 0'30 grms. or about 5 grains. 

 For a sheep 1"25 „ or about 20 grains. 

 Divided into two doses per day. 



It is now believed that the ova of these parasites, passed from 

 the body of their host, retained their vitality in damp places only, 

 and that where nice bites of green grass, such as that growing on 

 the sides of open drains and damp spots in pastures otherwise 

 dry, are sources of danger, the parasitic ova becoming ingested 

 with such grasses. The prevention of the disease by the 

 destruction of the worms should be attempted by first digging 

 up, where possible, all such green grasses, and inverting the 

 sods. 2d. By a liberal application of salt to the land, and, 

 where possible, an allowance of it to the sheep. 



During wet seasons the above precautions are impossible, and 

 all that can be done is to remove to the driest pastures, give 

 corn where possible, and an allowance of common salt in the food. 



STRONG YLUS TETKACANTHUS. 



In March 1873, an Iceland pony rising two years old, which 

 had been under my care for some weeks, died from what 

 appeared to be an exhausting disease, and, as stated in a letter 

 to Dr. Cobbold, there were no very marked signs of the presence 

 of parasites during life. The appetite was good ; there was no 

 cough ; and we were led to suppose that there were worms by the 

 absence of disease more than anything else. There was gradual 

 emaciation, but no diarrhoea, and at no time were the fseces 

 foetid. As bearing upon the discovery of this parasite, I may 

 state that Dr. Knox, who wrote in the Edinhurgh Medical and 

 Surgical Journal for 1836, says — " On two occasions my friend 

 Mr. Dick found parts of the large intestines of a horse present- 

 ing the following appearance : the gut being simply laid open 

 so as to exhibit the mucous membrane, a number of dark 

 spots are observed, evidently exterior to the inner membrane." 

 And, further on, speaking of the worms, he adds : " they 

 have no cyst, and vary from the tenth of an inch to a length 



