276 



that the "grubs" had already "got small holes opened to the 

 brain," when their further operations were, it was supposed, 

 suspended by the death of the subject! 



1 have had a singularly limited experience with any 

 diseases which could reasonably be attributed to the presence 

 of these parasites, and therefore do not feel myself at all well 

 qualified to judge of their actual effects on the sheep. That 

 want of experience is a strong proof of itself, that resulting 

 maladies are not as frequent by any means as is popularly 

 supposed. And knowing, as I do, that other and wholly 

 dissimilar diseases are habitually termed "grub in the head," 

 I can entertain no doubt that the extent of the injuries thus 

 inflicted is enormously exaggerated. 



Influenced by these latter considerations, and by the 

 strong counter testimony of such really able veterinarians as 

 Messrs. Clark and Youatt, and the silence on the subject of 

 Mr. Spooner and some other modern writers, I was formerly 

 led to doubt whether the larvae of the oestrus ovis ever did 

 more in the sheep's head than effect a degree of temporary 

 irritation of the lining membranes, which might produce 

 serious inconvenience when acting in concert with the 

 inflammation already established by catarrhal or other 

 cerebral affections, but which never caused death. Again 

 reminding the reader that I speak from a very limited 

 personal knowledge of the disease, I feel it due to frankness 

 to say that my opinions have undergone some change. The 

 testimony of intelligent men has satisfied me that the irrita- 

 tion and ultimate inflammation of the mucous lining of the 

 head produced by the tentacula of the worm and by its 

 constant feeding on the secretions if not even on the 

 substance of the membrane itself, in certain stages of the 

 disease,* are sufficient in some cases to cause death. I should 

 not expect a sheep in high condition and apjjarent health to 

 die suddenly from this cause without previous symptoms 

 of disease, and under circumstances resembling those 

 of apoplexy. I should not expect the powerful nervous 

 disturbances of epilepsy. But if the sheep began to fall 

 off rapidly in condition a little before the opening of spring, 

 without any other traceable cause — if it wandered round 

 with irregular movements, twisting about its head occa- 

 sionally as if it was suffermg pain — and esi)ecially if the 

 mucus discharged from the nose was tinged with blood — I 



* This may be more doubtful. 



