3o6 THE MANAGEMENT AND DISEASES OF THE DOG. 



caused by exposure to damp and cold, especially after being, 

 heated. The natural exhalation from the skin being sud- 

 denly checked, the water is retained in the bloodvessels, and 

 seeks an outpour elsewhere, and this either takes place in the 

 areolar tissue — producing anasarca, or in some of the serous 

 cavities of the body, frequently the peritoneal, and giving 

 rise to ascites. 



The analogy with human dropsy being very close, a brief 

 extract from Sir Thos. Watson's instructive lecture on this 

 subject will not be out of place. " To comprehend this rapid 

 change from a state of health to a state of dangerous disease, 

 we must again have recourse to the findings of physiology. 



" Besides the constant exhalation which takes place from 

 the inner faces of the shut serous cavities, a large amount of 

 watery fluid is continually thrown out of the system, by all 

 those services that communicate with the air by the skin, 

 the lungs, the bowels, the kidneys. 



" Now it is well ascertained that when the excretion of 

 aqueous fluid of one such surface is checked, the exhalation 

 from some other surface becomes more copious. 



" It is probable that the aggregate quantity of water thus 

 expelled from the system in a given time, cannot vary much, 

 in either direction, without deranging the whole economy. 

 But we are sure that the amount furnished by any excreting 

 surface may vary and oscillate within certain limits consist- 

 ent with health, provided that the defect or excess be com- 

 pensated by an increase or diminution of the ordinary 

 expenditure of watery liquid through some other channel. 

 Sound health admits and requires this shifting and counter- 

 poise of work between the organs destined to remove aqueous 

 fluid from the body. This supplemental or compensating 

 relation is more conspicuous in regard to some parts than to 

 others. The reciprocal but inverse accommodation of func- 

 tion that subsists between the skin and the kidneys affords 

 the strongest and the most familiar example. 



" In the warm weather of summer, when the perspiration 



