196 PHYSIOLOGY. 



tempt to explain the cause of some changes, which, in certain 

 circumstances, appear in the colour of the whole mass of blood. 



CCLV. We suppose that the red globules, when viewed 

 singly, have very little colour, and that it is only when a certain 

 number of them are laid one upon another, that the colour ap- 

 pears of a bright red ; but this also hath its limits ; so that, 

 when the number of globules laid on one another is consider- 

 able, the colour becomes a darker red. Upon this supposi- 

 tion, the colour of the mass of blood will be brighter or darker 

 as the colouring part is more or less diffused among the other 

 parts of the mass ; and we think this appears to be truly the 

 case from every circumstance that attends the changes which 

 have been at any time observed in the colour of the blood* 



CCLVL The gluten of the blood, from its resemblance, on 

 the one hand,, to the albumen ovi, and, on the other, to tire 

 matter of the solids of animal bodies, we consider as the principal 

 part of animal fluids, as that which is immediately formed of 

 the aliment taken in, and as that which is employed in increas- 

 ing the growth of the solids, or in repairing their waste. 



CCLVII. But it is well known that the animal fluids in gen- 

 eral, and particularly the gluten, is prone to putrefaction ; and 

 that, even in the living body, if fresh aliment be not constantly 

 taken in, and also if certain excretions which carry off putrescent 

 matter be not constantly supported, a considerable putrefaction 

 certainly takes place. From hence we are led to think, that 

 some approach to putrefaction constantly takes place, even in the 

 most healthy bodies ; and that it appears especially in an evolu- 

 tion of saline matter, and that this, taken up by the water con- 

 stantly present, forms the serosity. We suppose it is this which 

 affords the vapour of the blood (CCXLVIL), and that it is the 

 serosity dissolving a portion of the gluten which forms the se- 

 rum that appears upon spontaneous separation (CCXLVIL). 



CCLVIII. The saline matters impregnating the serosity, if 

 we may judge from the analysis of urine, are of various kinds ; 

 but particularly, there is present an ammoniacal salt, now well 

 known under the name of the essential salt of urine, which, if 

 not originally formed, is at least most copiously evolved in ani- 

 mal fluids. 



