198 BLOOD. 



even, wholly arresting, the coagulation of the blood, but the ques- 

 tion has not yet been definitely settled in relation to other alkaline 

 salts ; for in the experiments on different salts, no attention has 

 been paid to the degree of dilution of the saline solution, or to the 

 quantities of the solution employed. Nasse found, however, that 

 almost all salts accelerate coagulation when not employed in too 

 large quantities, although they may retard it when used in very 

 small quantities. On this account, it is far less easy than was 

 formerly supposed to determine the connection existing between 

 the quantity of the salts contained in the blood, and its more or less 

 rapid coagulation in different diseases. Thus the absence of 

 coagulability, which has occasionally been observed in the blood in 

 typhoid and putrid conditions, has been referred to a considerable 

 increase of the salts of the blood, or to the presence of alkaline 

 carbonates, but this is mere opinion, unconfirmed by any experi- 

 ments. All that can be asserted on this subject, therefore, is that 

 the difference frequently observed in the period in which the blood 

 coagulates in the same form of disease very probably depends 

 upon the amount of the salts contained in the blood. 



Viscid solutions of indifferent organic substances, such as albu- 

 men, casein, and sugar, appreciably retard the coagulation of the 

 blood. This circumstance shows us, at all events, how many 

 different conditions may coincide to bring about one or another of 

 these results in reference to coagulation. But here, unfortunately, 

 we derive only little aid from chemical analysis ; for, as we have 

 already observed, we are still in entire ignorance as to the different 

 quantities of salts occurring in the blood during disease. 



The influence of the temperature of the blood (as it escapes 

 from the body) on its coagulation, has also been noticed by 

 Nasse, but we are still ignorant how far this may effect the period 

 of the coagulation. The difficulties of investigating more closely 

 the causal connection of the period of coagulation and the external 

 and internal relations of the blood, are further increased by the 

 circumstance, that while these influences are frequently manifested 

 in the blood, they may simultaneously neutralise one another in a 

 greater or lesser degree. 



It has likewise been conjectured that the blood when it is rich 

 in fibrin (inflammatory blood) coagulates less rapidly than when it 

 is deficient in that substance ; but as the reverse is frequently found 

 to occur, it appears very doubtful whether the quantity of fibrin 

 exerts any influence whatever on the period of coagulation. 



In the present state of our knowledge, in reference to the dif- 



