CAUSE OF COAGULATION OF THE BLOOD. 157 



On the other hand, we are not justified, with Robin and 

 Yerdeil, in abandoning the subject with the assertion that 

 it is " as vain to seek after the cause of this fact as to inquire 

 why fibrin exists, why sulphate of copper is blue, etc." ; * 

 assuming that fibrin coagulates merely because it has ,the 

 property of coagulation, as albumen is coagulated by heat, 

 or ca seine by acetic acid. An extension of this method in 

 physiology would put an end to all generalization, restricting 

 the operations of the intellect to the mere observation of 

 phenomena. 



Circulating in the organism, the plasma contains, molec- 

 ularly united with each other and uniformly distributed in 

 the fluid, fibrin, albumen, salts, and volatile substances. 

 Albumen retains its fluidity out of the body, until heat or 

 some coagulating agent is applied ; but by employing a 

 current of galvanism, which we know changes the condition 

 of the inorganic substances in the serum, something is taken 

 away which causes albumen to coagulate, or which, when it 

 existed unchanged, retained albumen in its fluid condition. 

 Is it not possible that the blood while circulating may contain 

 a substance capable of keeping fibrin fluid, the evolution of 

 which out of the body is the cause of coagulation ? We are 

 particularly led to ask this question, as we are acquainted 

 with many substances which possess this property when added 

 to blood drawn from the vessels ; such as carbonate of soda, 

 ammonia, etc. This idea forms a fit basis for experimental 

 inquiry, by a study of the substances evolved by the blood 

 during coagulation in the form of vapor. If it be objected 

 that no coagulation takes place in the vessels, while an op- 

 portunity for volatilization is constantly presented in the 

 lungs in normal circulation, it must be remembered that the 

 blood is continually washing out, as it were, in the course of 

 circulation, matters formed in the various parts of the organ- 

 ism ; and substances which are continually discharged by the 

 lungs, skin, kidneys, etc., are necessarily as continually taken 



1 ROBIN and YERDEIL, op. cit., tome Hi., p. 210. 



