560 PRACTICE OF PHYSIC. 



division, another effect of heat which is to be particularly ob- 

 served, is that of increasing the putrid tendency of the fluids. 

 It has been supposed to act upon some of them more than upon 

 others, and particularly upon the bile ; hence the opinion that 

 the bile is the most putrescent of the animal fluids ; but with- 

 out discussing that matter, we may allow the fact, that hot -sea- 

 sons have an effect upon the bile, and that it is liable to be 

 poured into the intestines in larger quantity ; and from its ef- 

 fects it would also appear to be possessed of unusual acrimony. 

 (See LI.) 



" With regard to this division, Sydenham has supposed that 

 the seasons varying those states of diseases, commence with the 

 solstices, and not with the beginning of spring or of autumn ; that 

 the vernal diseases commence at the winter solstice, and the au- 

 tumnal at the summer ; or the one at the shortest, the other at 

 the longest day. This is perhaps the only term that can be 

 fixed, but it may be considerably different in different places ; 

 and it is perhaps more applicable to Britain than to other 

 countries ; for in warm countries, the season of putrid diseases 

 comes on before the summer solstice, and in cold climates the 

 season of inflammatory diseases comes on sooner than the winter 

 solstice, or towards the end of harvest. 



" So far with respect to the influence of the sensible qualities 

 of the air upon the general causes of epidemics, but the same 

 qualities have also an influence upon the type. Thus, the 

 winter season generally determines fevers to be continued, and 

 very often to be of the inflammatory kind ; the same fevers in 

 the spring, upon the cold diminishing, become intermittents ; 

 and in summer, the heat, acting as a stimulus, brings them back 

 again into the continued form ; for though I have said, accord- 

 ing to general observation, that long continued heat takes off 

 the inflammatory diathesis, yet by the stimulus it affords, it has 

 analogous effects to every other stimulus ; and so may modify 

 diseases by producing the inflammatory diathesis. Upon the 

 remission of the heat in autumn, the fevers will again become 

 intermittent ; and in the form which has the most distant periods, 

 the quartan. 



** Now, these effects of the sensible qualities of the air will 



