58 CROONIAN LECTURES 



stances, one of which acts as the fibrinogenic 

 matter. 



Those who still think that vital action must 

 be concerned in the coagulation of the blood 

 will probably say that it is the principle of life 

 that stops the mutual action of these two sub- 

 stances in healthy circulating blood. 



The chemist will before long solve the 

 problem why these two substances do not 

 always act upon one another, since they can 

 both be got out of the blood. The most 

 probable answer is, that there is some slight 

 difference of composition between these sub- 

 stances as they exist in circulating blood and 

 as we obtain them from blood that has been 

 drawn from the body. The fibrinoplastic sub- 

 stance is rapidly acted on by ozone. The 

 fibrinogenic substance also is rapidly changed 

 after it is formed, so that possibly the necessary 

 quantity of these substances is not given the 

 necessary time to act upon one another for the 

 production of coagula. 



The second of the unfinished discoveries 

 which I wish to bring before you relates to the 

 subject of digestion. 



In Dr. Prout's Bridgewater Treatise (p. 493), 



