573a SPOEADIC DISEASES. 



vations outside the animal body. They, however, presented 

 themselves with great constancy in cultivations of the spinal 

 fluid and myxredema — jelly-like material— under every possible 

 variation, produced by change of media, place, and manner of 

 experimenting. It must therefore be surmised that they are 

 either various stages in the life history of the same organism, 

 or that, as in some other diseases, multiple organisms are present. 

 As an organism certainly more nearly allied to the moulds than 

 to any pathogenic type previously described, it is interesting as 

 being, so far as I am aware, the first known instance of what 

 appears to be a mould, in one stage at least, proving capable of 

 producing pathogenic effects upon the higher animals, and it is 

 also interesting to note that this pathogenic property is pro- 

 bably acquired after passage though the body of the tick, a 

 state of matters now found to exist in other diseases. 



When this disease was first investigated by me, the influence 

 of the tick in inducing the so-called Texas fever, and other 

 similar sources of inoculation, had not been investigated ; but 

 now it is proved beyond all doubt that the tick disease, as well 

 as other diseases communicated by insects, is now known in 

 various parts of the world. 



One remarkable circumstance might, in conclusion, be added, 

 viz., that whilst in this country the tick is but seldom injurious 

 to other animals than sheep, in other parts of the world its 

 pathogenic effects are mostly confined to horned cattle, although 

 it attacks human beings, sheep, horses, mules, &c. 



NEURITIS — NEURALGIA. 



Inflammation of the Nerves — Neuritis. — When one considers 

 the very delicate organisation of nervous tissue, and the extreme 

 sensibility of the sensory nerves, a most striking fact presents 

 itself, — namely, the rarity or almost total absence of inflam- 

 mation of the nerves. The nervous substance contained within 

 the cranium, as well as that constituting the spinal cord, is 

 subject to inflammatory changes ; but it may truly be said that, 

 except as a result of blood alteration — as in azoturia, where the 

 sciatic nerves, and traumatic tetanus, where tlie nerves con- 

 nected with the wound and their neurilemmas are often found 



