116 CIRCULATING FLUIDS: 



The blood of frozen and apparently dead frogs remains flviid, 

 and tlie same is the case in liybernating animals, in which the 

 temperature of the blood is reduced to that of cold-blooded 

 animals. ^ 



The coagulation of the blood is retarded by contact with 

 animal membranes ; it will remain fluid in tied arteries for tlie 

 space of three hours. Blood which has been infused into the 

 cellular tissue ■odll remain fluid for weeks. Schultz has ob- 

 served that blood which has collected in the intestines remains 

 fliuid for a long time ; moreover, the blood which has been 

 abstracted by leeches does not coagulate, as long as it remains 

 in the body of the animal.^ 



Gerhard, Ilufeland, and Kielmeyer have shown that blood 

 through which an electric current is continuous!}^ passed re- 

 mains fluid for a long time. Schubeler also shoAved that 

 positive electricity hinders the coagulation of the blood ; more- 

 over, the blood of animals killed by electricity or lightning 

 does not coagulate. 



The following salts hinder the coagulation of the fibrin, 

 according to Hewson,^ Schultz,"* and Hamburger^s* observa- 

 tions : sulphate of soda, chloride of sodium, nitrate of potash, 

 chloride of potassium, acetate of potash, and borax, if they be 

 added in the proportion of half an ounce to six ounces of 

 blood. If however the blood be diluted Avith double the quan- 

 tity of water, the fibrin coagulates. (Hewson.) The carbo- 

 nates and acetates prevent the coagulation of the blood, in 

 all degrees of concentration. With regard to the action of 

 the sulphates, a concentrated solution appears to retard the 

 coagulation ; a dilute solution, on the contrary, to accelerate it. 

 (Hamburger.) The same appears to be the case with respect 

 to the tartrates and borates. 



The following metallic salts impede the coagulation of the 

 fibrin : sulphate of copper, ammoniaco-sulphate of copper, sul- 

 phate of the protoxide of iron, chloride of iron, feiTocyanide 



' Schultz, op. cit. p. 80. 

 * L. c, pp. 64 and 81. 



^ Disquisitio experimentalis de sanguinis natiu'a. L. B. 1785. 

 " Op. cit. 



' Experinientorum circa sanguinis coagulationem specimen primum diss, inaug. 

 auct. Hamburger. Berolini, 1839. 



