CHEMICAL EXAMINATION OF THE BLOOD. 321 



Estimation. In order to determine the amount of fibrin in a 

 given volume of blood, from 30 to 40 c.c. are placed in a previously 

 weighed beaker, which is closed with an India-rubber cap. Through 

 the centre of this passes a piece of whalebone that is firmly fixed 

 and provided with a rudder-like end, which dips into the blood. 

 This is now defibrinated by beating with the whalebone paddle, 

 when the beaker is again weighed with its contents. The differ- 

 ence, as compared with the first weight, indicates the weight of the 

 blood. The beaker is then filled with water and the mixture again 

 beaten. The fibrin is allowed to settle, and after being washed by 

 decantation with normal salt solution it is collected on a filter of 

 known weight. On this it is further washed with normal salt solu- 

 tion until free from coloring-matter ; it is then extracted with boiling 

 alcohol, then with ether, and finally dried at 115 C. and weighed. 



Other albumins in addition to those already considered are not 

 found in normal serum. Under pathological conditions, however, 

 nucleo-albumins and deutero-albumoses may be encountered. They 

 will be considered in future chapters. 



The remaining solids which are found in both plasma and serum 

 are, as has been pointed out, present in only very small amounts. 

 The most important of these is glucose. Its amount varies between 

 1 and 1.5 pro mille, and is but little influenced by the character of 

 the food unless a large excess of carbohydrates has been ingested. 

 In such an event the amount may increase to 3 pro mille, or even 

 higher, but it then appears also in the urine, whereby a further 

 increase is prevented. Larger amounts, such as 9 pro mille, are 

 found only under pathological conditions. 



It is interesting to note that after blood has been shed the glucose 

 rapidly diminishes in amount. This phenomenon is thought by 

 some to be due to the action of a special ferment, the glucolytic 

 ferment of Lepine. It is supposedly derived from the leucocytes, 

 and, according to Lepine, is eliminated into the blood by the pan- 

 creas. Arthus and others regard this process of glucolysis as a 

 post-mortem change, but there is reason to suppose that the activity 

 of the glucolytic ferment is exercised also during the life of the 

 animal, and is possibly of fundamental importance in the metabo- 

 lism of glycogen. Whether Lupine's ferment is identical witli 

 another ferment which was found in the blood, and has been studied 

 by Rohmann and Bial, and which is said to transform starch and 

 glycogen into glucose, remains to be seen. 



In addition to glucose, another reducing substance is found in the 

 blood, which to a certain degree is fermentable and is soluble in 

 ether. From the researches of P. Mayer, it appears that this sub- 

 stance is a conjugate glucuronate. The presence of jecorin, on the 

 other hand, which has repeatedly been reported, is doubtful. 



Animal gum has also been found in small amounts (0.015 per cent.). 



Glycogen. Glycogen is constantly present in normal blood. Its 



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