FEVERS. 613 



pulse, and where venesection was practised with very evident 

 relief, I am clearly of opinion that this matter is to be studied 

 more anxiously than it has hitherto been done." 



6. The age, vigour, and plethoric state of the patient. 

 " The fulness and vigour of the constitution may not be al- 

 ways distinctly marked, but we may presume its existence when 

 the patient is young. The plethoric state of the system gener- 

 ally prevails from the age of puberty to that of manhood, com- 

 monly from fourteen to thirty-five years. In the course of these 

 years a variety may again occur, as the solids increase in firm- 

 ness and solidity ; and I believe, that the inflammatory tendency 

 is most frequent from twenty-one to thirty. The judgment 

 from age, however, is not to be solely trusted to, as many persons 

 even at that age are of a weak, relaxed habit." 



7- The patient's former diseases and habits of blood-letting. 

 " There are constitutions of a peculiarly inflammatory ten- 

 dency, which are exposed to Angina, to rheumatic and to peri- 

 pneumonic affections ; and although such symptoms do not 

 evidently appear, if they have frequently occurred formerly, 

 this must determine us to blood-letting. Another remarkable 

 constitution is the hsemorrhagic. Thus, if a person has been 

 frequently liable to bleeding at the nose, especially after the 

 age of puberty, he will bear blood-letting better, and it will be 

 the more necessary." 



8. The appearance of the blood drawn out. " There is no- 

 thing in which physicians are more rash and presumptuous, than 

 in ascertaining the condition of the blood from its appearance 

 when extravasated. In one case the blood forms entirely one 

 crassamentum, and is therefore easily in danger of obstructing 

 every vessel of the body ; in other cases they find various de- 

 grees of density in the crassamentum, and various proportions 

 of serum, which gives occasion to the like sort of judgment. 

 But we know now that these reasonings are fallacious, and that 

 there is a great variety of circumstances from the condition of the 

 orifice in the vein, the manner in which the blood flows, and the 

 temperature of the air, and that the appearance is very much 

 regulated by the vessels in which the blood is received. In the 

 Royal Infirmary, the use of tin plates gives occasion to a parti- 

 cular appearance of the blood, which does not occur in private 



