ACUTE RHEUMATISM. 243 



fatigue with exposure, without sufficient attention to sudden 

 alternations of temperature,particularly when accompanied with 

 excess of moisture in the atmosphere, and probably also age. 

 We are aware that when examined carefully these inducing 

 agencies are found to operate with singular irregularity, are 

 often disappointing and always erratic ; it is, however, abun- 

 dantly certain that, with animals possessing the constitutional 

 predisposition, their exposure to such extrinsic influences as 

 indicated is more likely to be followed by the exhibition of 

 symptoms of rheumatism than others where this inherited 

 constitutional tendency is unmarked. 



Of the directly operating agencies some appear more powerful 

 or more constantly in operation than others, such as age — the 

 young being more liable than the matured — and what are 

 spoken of as atmospheric. That young animals should suffer 

 more from coincident depressing influences is not to be 

 wondered at ; in them all those functions subservient to the 

 development of the body are in the most vigorous operation, 

 this very functional activity rendering them more susceptible 

 to -the action of adverse agencies. The small amount of 

 exercise to which they are often compelled to submit is injurious 

 from the enforced inactivity to which the joints are subjected ; 

 while it not unfrequently happens that they are turned in great 

 haste, without preparation, from too warm paddocks and close 

 confinement into the open air and perfect liberty — the transi- 

 tion is too great, both as to temperature and exercise. 



When referring the immediately developing causes of rheu- 

 matism to atmospheric influence, location, and disturbed nutri- 

 tion, there is little doubt that we are speaking of agencies the 

 exact mode of whose operation we may be unable satisfactorily 

 to explain. 'Atmospheric influence' is a term of much ambiguity, 

 and is often employed to veil our ignorance. There are, how- 

 ever, certain conditions of the atmosphere, as its temperature, 

 its moisture or dryness, etc., the actions of which we can with 

 tolerable certainty predict. Even when very young, animals 

 can with impunity endure a comparatively low temperature if 

 imaccompanied with moisture ; when, however, a damp lair is 

 added to a dry cold wind, a very actively exciting cause of 

 rheumatic inflammation of the joints exists ; the animals are 

 disposed to lie, the circulation becomes flagging, and if there 



]6— 2 



