ANIMAL HEAT. 



677 



ceases after a certain interval of variable extent, 

 according to various circumstances ; and 

 a state of tranquillity comes on in which the 

 body has recovered the faculty of engendering 

 by the ordinary means the quantity of heat ne- 

 cessary to the comfortable existence of the in- 

 dividual. After this the repetition with greater 

 or less frequency of the same acts ends by 

 restoring the calorific function to the state in 

 which insensible reaction suffices to maintain 

 it in its sufficiency. In the first case it is a 

 strong individual able to make the voluntary 

 and energetic efforts required to remedy the 

 inconvenience he suffers. In the other instance 

 it is an individual who has not the strength 

 requisite to make such efforts. In this case 

 nature supplies the deficiency by exciting 

 directly the motions of circulation and respira- 

 tion by the painful impression of cold. Al- 

 though the condition of the first be the state 

 of health, and that of the second properly a 

 morbid state, they nevertheless have many 

 relations in common, which differ princi- 

 pally in degree. Does not the robust indivi- 

 dual experience an inconvenience for which he 

 finds a remedy in violent and repeated efforts? 

 However robust he may be under ordinary cir- 

 cumstances, in the extraordinary condition in 

 which he is placed the usual vital processes 

 no longer suffice him. He must have recourse 

 to violent means which disturb the economy ; 

 and by a repetition of the same efforts at diffe- 

 rent periods, that is to say, in fits or paroxysms, 

 he ends by so far fortifying himelf as to be able to 

 do without them. Is not this tantamount to 

 remedying a relative infirmity of constitution ? 

 Let its degree increase but a little, and the 

 infirmity becomes disease. This parallel is not 

 founded on vague and superficial resemblances, 

 but on determinate and fundamental relations. 

 There is not one essential point in the compari- 

 son which does not rest on the result of direct 

 experiments, most of which have been quoted 

 in preceding parts of this article. What must 

 be done to justify the similitude of these 

 two states ? With regard to the state of health 

 the connexion of phenomena having reference 

 to the hygienic and voluntary reaction is well 

 known. With reference to the relation between 

 the symptoms in the morbid state and the 

 morbid reaction, it remains to be proved that 

 under circumstances where there is but slight 

 production of heat, the feeling of cold may 

 induce acceleration in the respiratory and circu- 

 latory motions. Now it has-been established by 

 experiments already quoted, that there is reac- 

 tion of this precise kind in such circumstances. 

 We have seen, for instance, that when a bird, 

 naked or scantily covered with feathers, is 

 taken from the nest and exposed to the air 

 even in summer, it speedily begins to shiver, 

 and to exhibit a reaction in accelerated motions 

 of respiration, which is followed by, and indeed 

 implies increased rapidity in the motions of 

 the heart and current of the blood. It were 

 also proper to show that the cold state may, by 

 means of the violent and involuntary reaction, 

 induce the restoration of heat. This is also 



susceptible of proof by means of direct expe- 

 riment. To this end an individual (a young 

 bird from the nest) must be chosen of such 

 an age that the temperature will not be apt to 

 fall too low on exposure to the air. If the 

 choice have been fortunate, it will be found that 

 the temperature sinks in the first instance, and 

 then rises, so that it may even surpass the de- 

 gree it showed at first, under the influence of 

 the reaction occasioned by the acceleration of 

 the motions of respiration and circulation. 

 The proof here is, therefore, extremely satis- 

 factory. A creature in a state of health is taken 

 and placed in circumstances in which the same 

 essential symptoms are produced in the same 

 order as in the morbid state which we have 

 described. It can scarcely be necessary to say 

 that the morbid state which we have described 

 in man is that of simple intermittent fever. 

 Not only in the beginning of this disease is 

 there a feeling of cold, but recent accurate ob- 

 servations have shown, by means of the ther- 

 mometer, that there is actual refrigeration. 

 There is, therefore, lesion of the calorific func- 

 tion in the sense previously indicated, that is, 

 there is decrease in the power to produce heat. 

 Subsequently the temperature rises whilst 

 there is still more or less of the sensation of 

 cold remaining ; but this only happens by vir- 

 tue of a general disposition of the nervous 

 system. The same thing, in fact, occurs in a 

 state of perfect health ; when the body has for 

 some time been exposed to severe cold, the 

 sensation continues for a certain interval after 

 it has been restored to the normal temperature. 

 It is of little consequence, as regards the sub- 

 ject which engages our attention, that there are 

 some intermittent fevers which do not exhibit 

 the phenomena of temperature that have been 

 described. We are only interested in proving 

 that some do occur which present them all, a 

 fact that has been demonstrated by the best 

 authorities. 



There is consequently in these cases a lesion 

 of the calorific function, a lesion of which the 

 essence consists in a diminution of the faculty 

 of producing heat. In a constitution capable of 

 re-acting by the acceleration of the respiration 

 and circulation, we may observe upon this occa- 

 sion two principal modifications of the morbid 

 state, which both depend on the same cause, 

 but which differ in degree. The first is that 

 described in which the reaction suffices to 

 restore the calorific power to the degree com- 

 patible with health after one or more fits or 

 paroxysms. W r ith regard to the second, the 

 diminution of the function of calorification may 

 be so great, that the reaction may prove in- 

 adequate to restore it, not only permanently 

 but even momentarily. There are in fact 

 diseases of this kind ; there are many regular 

 intermittent fevers that have no tendency to 

 spontaneous cure ; there is also one particular 

 form of the disease which proves speedily fatal 

 without the intervention of art. This is that 

 form of intermittent which is known at Home 

 especially under the name of \\\ejebbrc afgidtt, 

 or cold fever. It often happens that the patient, 



