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glands specially set apart for the purpose. The lecturer then 

 explained the process of coagulation. The following are some 

 of the facts to which he alluded on this subject : — The rapidity 

 with which a coagulum is formed, and also its amount, con- 

 sistence, and composition, are affected by a variety of circum- 

 stances. When cold blood is warmed it coagulates, and when 

 warm blood is further heated it coagulates. Contact with 

 foreign bodies promotes and accelerates the process. This 

 explains why when a needle is introduced into a bloodvessel 

 of a living person, a coagulum forms itself round it — a circum- 

 stance of which advantage has been taken in the treatment of 

 disease. It also accounts for the fact that when the coats of 

 a bloodvessel are diseased, and thereby act as foreign sub- 

 stances, the walls of the vessel become coated with coagulum. 

 Arrest or retardation of motion is favourable to coagulation. 

 The addition of water at first promotes coagulation, but when 

 the quantity is large it stops the process. A low specific 

 gravity of the blood favours coagulation. Almost all sub- 

 stances added in small quantity promote, but in large quantity 

 retard the formation of a clot. An atmosphere of ammonia 

 prevents coagulation; and hence probably the similar effect 

 produced by tobacco smoking, which causes an increase in the 

 amount of ammonia present in the blood, and at the same time 

 produces languor and debility. It has been observed that of 

 boys educated in the same schools in Paris, those who used 

 tobacco never stood as high in the prize list as those who did 

 not. It must be admitted, however, tbat tobacco smoking 

 did not prevent the German boy from thrashing the French 

 boy, while the English boy looked on. That condition of 

 the system which accompanies faintness promotes coagulation. 

 The blood appears incapable of yielding a clot, after poisoning 

 by antimony, phosphorus, arsenic, amylene, &c, or after 

 death from cholera or typhus fever. The blood of a turtle 

 may be kept fluid by its own living heart, or that in a tortoise 

 for days ; but it will at once coagulate when allowed to escape. 



