COAGULATING LYMPH OF THE BLOOD. 179 



or the juice of the flag, (iris versicolor,) which are both made 

 green by it. Sulphur combined with ammonia, is also found 

 in it. Owing to the presence of sulphur, serum has the effect 

 of blackening silver when left in it, and also has its power of 

 dissolving the oxydes of mercury, iron, copper, and other me- 

 tallic preparations. 



SECT. II. OF THE COAGULATING LYMPH -OF THE BLOOD. 



Coagulating lymph, or fibrine, when circumstances are suita- 

 ble for collecting it, freed. from the red globules, offers the ap- 

 pearance of a semi-transparent body of a very light drab colour; 

 it is elastic and strong, and, when subjected to the microscope, 

 has the appearance of muscular fibres, by being composed of 

 colourless globules. Like muscta, it also, when macerate^ in 

 water, resolves itself into those globules before it putrefies. 



If the blood, while flowing from an animal, be collected, and, 

 at the same moment, stirred round and round with a rough 

 stick, the fibrine will gather upon the latter in a fibrous form, 

 so as to resemble a mass of entangled and knotted packthread. 

 The fibrine may be afterwards washed almost white, and, at 

 any rate, so as to clear it entirely from the red globules. 



The fibrine, when dried, loses greatly in its bulk and weight, 

 by the evaporation of the serum from it, so that the proportion 

 which it seems to bear to the whole mass of blood is much less 

 considerable than one would suppose from seeing it in the sim- 

 ple coagulated state. 



The coagulating lymph of the blood being common, proba- 

 bly, to all animals, while the red particles are not, we must 

 suppose it from this alone to be the most essential part; and, 

 as we find it capable of undergoing, in certain circumstances, 

 spontaneous changes, which are necessary to the growth, con- 

 tinuance, and preservation of the animal; while to the other 

 parts we cannot assign any such uses, we have still more rea- 

 son to suppose it the most essential part of the blood in every 

 animal."* 



* Hunter, loc. cit. 



