NATURE AND CAUSATION. 485 



subjects develop broncliial or common catarrli. Passive con- 

 gestion is encountered under conditions associated with retarded 

 venous circulation or depressed heart-action, as in mitral and 

 some other cardiac disturbances, and in general exhaustion 

 attendant on some fevers and debilitating diseases. 



Active congestion, the most frequently occurrmg form in the 

 horse, may be observed to a certain extent, but not to that of 

 disease, accompanying all active exertion. In well-developed 

 pulmonary hyper?emia we have functional activity in excess 

 until this induces impairment, or, it may be, arrest of func- 

 tional power. When the rate of speed or power with which 

 the blood is driven to and through the lungs is excessive, 

 there must speedily bo a certain amount of relief, either 

 by diminished rapidity of circulation, increased cardiac or 

 pulmonary power, or the result is a fatal accumulation of blood 

 in the pulmonary capillaries, terminating in pulmonary inac- 

 tion. Rupture, in these cases, is rarely sufficiently extensive 

 to produce even temporary relief Of this irregularity and 

 stagnation in the flow of blood through the pulmonary vessels 

 we observe many grades or variations as to extent, from the 

 simple turgescence of active exertion, and the somewhat dis- 

 tressed pulmonary condition connected with defective cardiac 

 action, to the perfect engorgement and rupture of capillary 

 structure incident to an excited and continued circulation over- 

 powering both heart and lungs. 



Of increased cardiac action operating in the production of 

 pulmonary congestion we have the most striking examples in 

 those instances which follow attempts to hunt raw or unj)re- 

 pared horses. These examples and warnings, we fear, nearly 

 invariabl}^ follow from overlooldng the fact that horses are 

 living machines, and that for the comfortable performance of 

 even moderate work they must have their living organism kept 

 in regular action, while for the execution of extra work that 

 organism requires to be in a high state of preparedness. For 

 this latter the animal's powers must be gradually developed and 

 maintained in a high state of efficiency ; he must, as horsemen 

 say, be in fairly good ' condition.' This state of ' condition ' 

 does not consist in the possession of a full amount of flesh, nor 

 yet in a glossy coat, nor even in high spirits ; a horse may 

 possess all these, and yet be in an unfit state to undergo severe 



