REGENERATION OF BLOOD. 299 



salts of the plasma and to form fibrin-ferment (thrombin), intra- 

 vascular coagulation being the result. 



6. That under other conditions either the shedding out of 

 nucleoproteid from the corpuscles or its interaction with the lime 

 salts of the plasma may be altogether prevented and the blood 

 rendered incoagulable, unless nucleoproteid is artificially added, 

 or unless a modification of the conditions is introduced which will 

 permit of the interaction of the nucleoproteid with lime to form 

 ferment. 



7. That the nucleoproteid (prothrombin) is incompetent, in the 

 entire absence of lime salts, to promote the transformation of 

 fibrinogen into fibrin ; but, as a result of its interaction with lime 

 salts, it becomes transformed into a ferment (thrombin), which, 

 under suitable conditions of temperature, and the like, produces 

 fibrin. 



8. That either the place of nucleoproteid in coagulation may 

 be taken by certain albumoses, such as those found in snake-venom, 

 and by certain colloidal substances, such as those prepared by 

 Grimaux ; or that such substances may act by setting free nucleo- 

 proteid from the leukocytes and other elements in the blood, or 

 from the cells of blood-vessels, and thus indirectly promote coagu- 

 lation. 



The colloidal substances referred to in paragraph 8 were three in 

 number, and were artificially prepared by Grimaux, and presented 

 many of the characteristics of proteids. They all gave the xantho- 

 proteic reaction and in other ways resembled the proteid class. 

 Thus when injected into the veins of animals, as the dog, cat, or 

 guinea-pig, they caused intravascular coagulation, resembling in 

 this respect nucleoproteid. It is suggested by Schafer that they 

 produce this eifect not directly, but by setting free the nucleo- 

 proteid from the leukocytes, inasmuch as there is no disintegration 

 of the red or white corpuscles, nor any apparent change in the 

 epithelium of the vessels. 



Regeneration of Blood. One of the striking peculiarities 

 of the blood is the rapidity with which it is renewed after hemor- 

 rhages. The blood constitutes about 7.7 per cent, of the weight 

 of an adult ; and it is estimated that a hemorrhage in which no 

 more than 3 per cent, of the weight is lost will not be fatal, and 

 that the plasma will be renewed in such cases within forty-eight 

 hours, although it may require weeks for a renewal of the red 

 corpuscles. In the treatment of severe hemorrhages it is now the 

 practice to inject into the veins physiologic salt solution (p. 81). 

 The rationale of this is stated by Howell to be that in normal 

 blood the number of red corpuscles is greater than that necessary 

 for a barely sufficient supply of oxygen, and that if after a hemor- 

 rhage the quantity of fluid in the vessels is increased, the circula- 

 tion is made more rapid, and the remaining corpuscles are made 



