182 THE BLOOD. 



11. Diluted plasma which has been treated with carbonic 

 acid gas does not coagulate, even when shaken with air and 

 subjected to the temperature of the body (40 C.). 



From the above experiments we learn that plasma contains 

 two albuminous compounds, precipitable by carbonic acid gas 

 and by acetic acid; that one of them (paraglobulin) exists 

 alone in serum in considerable quantity; that the other (fibrin- 

 ogen) exists alone in liquids effused into uninflairied serous 

 cavities in very small quantity; that when paraglobulin is 

 added to these effusion-liquids they become coagulable, just as 

 serum may be made coagulable by the addition of fibrinogen. 



5. Heynsius's Experiment. 1 From the properties of 

 blood plasma demonstrated in the above experiments, we are 

 apt to infer that this liquid is the exclusive source of the fibrin 

 formed when blood coagulates. There is reason, however, for 

 believing that a very considerable quantit} r of fibrin-producing 

 material is contained while the blood is circulating, in the col- 

 ored or colorless corpuscles, for it can be shown that if these 

 elements are separated as completely as possible by subsidence 

 and decantation from a known quantity of blood, and added 

 to a similar quantity of serum, this serum acquires the pro- 

 perty of coagulating ; and the quantity of fibrin produced bears 

 a very considerable proportion to the whole quantity which the 

 blood would have yielded. Fifty cubic centimetres of blood 

 are received directly from the vein of a horse or ass into a 

 measuring tube surrounded with ice. The blood is immediately 

 afterwards poured into a tall narrow glass cylinder, which 

 alread}* contains half a litre of a two per cent, solution of coin- 

 inon salt, previously cooled by standing in ice. In this vessel 

 the mixture |s allowed to remain until the corpuscles have sub- 

 sided, after which the liquid must be drawn off with the aid of 

 a capillary pipette or syphon. The remainder is then mixed 

 with a similar quantity of salt solution, again left to itself sur- 

 rounded by ice, and the process repeated. Fifty centimetres 

 of serum of ox blood previously prepared, having been then 

 added to the corpuscles which remain at the bottom of the 

 vessel, the mixture is placed in water at a temperature of 40 

 C. After two or three minutes coagulation takes place. The 

 clot is collected and wasfied, dried and weighed. In the mean 

 time the fibrin yielded by an equal quantity of blood is deter- 

 mined. On comparing the weights, it is found, as before stated, 

 that the coagulum obtained from the mixture of serum and cor- 

 puscles alone, is nearly equal to that obtained from the whole 

 blood (corpuscles and plasma). It has been further shown by 

 Hey n^sius, that if blood is received in an ice-cold, half per cent., 

 or one per cent., solution of common salt, the quantity of fibrin 



1 Pfliiger's Archiv. B. III. p. 419. 



