BLOOD. 147 



from 1°'8 to 2°-6, the increased temperature that succeeds 

 violent exercise may probably be in part accounted for by this 

 means. 



Metamorphosis of the blood in the nutrition of the organism. 



The conversance of nutriment to the various parts of the 

 organism is one of the most important functions of the blood ; 

 and in order to discharge it efficiently, the blood must itself 

 receive a constant supply of proper material. 



Regarding the blood physically, as composed of corpuscles 

 and plasma, it is only from the latter that the organs can di- 

 rectly obtain nourishment. This plasma is, however, a very 

 complicated fluid; its principal constituents are albumen, 

 fibrin, fatty compounds, salts, extractive matters, and a pe- 

 culiar colouring matter, hsemapliEein. The question now arises, 

 Are all these constituents, or only some of them, employed in 

 nutrition? Our analyses of urine, sweat, and mucus show 

 that these secretions and excretions carry oflP, in addition to 

 certain peculiar matters, the same pigment, the same salts, 

 and the same (or similar) extractive matters as are contained 

 in the plasma ; hence we may infer that those substances 

 which are removed from the body are effete products of the 

 metamorphosis, and that they are not suited for nutriment, at 

 any rate in the form in which they occur. Neither albumen, 

 fibrin, nor fati is found in urine, sweat, or mucus, and the 

 presence of either albumen or fat is always regarded as a 

 sjonptom of a morbid state. This fact tends to support the 

 opinion that albumen, fibrin, and fat are the substances which 

 are employed in the nutrition of the peripheral system. 



The blood, in its passage through the capillary network, 

 permeates all organs and tissues, and their cells take up from 

 the plasma those substances which they requii'e for nutrition, 

 and restore to it those which have become effete, and are no 

 longer adapted for the process of nutrition. We may con- 



' The fat that is occasionally to be detected in the sweat does not arise from the 

 true perspiration, but from the sebaceous glands of the skin. Perfectly normal 

 mucus, such as occurs in some quantity in healthy urine, contains neither albumen 

 nor fat. Pulmonarj- mucus and the saliva discharged with it often contain a little 

 fat and albumen, but, in all probability, they belong to the saliva only, a fluid not 

 intended to be excreted. 



