PHYSIOLOGY. 161 



It appears likewise that this oil does not remain separate from 

 the other fluids of the alimentary canal, but is very accurately 

 diffused in the chyle ; which may be considered as a step to- 

 wards a more intimate mixture. 



" 2dly, That such a mixture actually takes place, is very pro- 

 bable from this, that no chyle appears in the left ventricle of 

 the heart, nor in the arteries and veins which carry the blood 

 which has passed through that ventricle. If there be some in- 

 stances of such appearance, which have been alleged, they are 

 certainly, however, very rare, and probably morbid. 



"3dly, Not only no chyle, but neither does any oil ever appear 

 in any part of the mass of blood, nor ever in any part of the 

 human body, till it appears in the cellular or adipose membrane, 

 into which it is probably brought by a peculiar secretion. It 

 has indeed been alleged, that oil has sometimes appeared on the 

 surface of extravasated blood or serum ; but in all such instances, 

 we presume it to have been a preternatural appearance : for in 

 the many hundred instances in which I have looked upon the 

 human blood, I have never met with any appearance of that 

 kind ; and whilst oil is so constantly and copiously taken into 

 the body, nothing can account for the absence of its appearance, 

 but the supposition of its having undergone an intimate mix- 

 ture with the other parts of the blood. 



" Some physiologists have been fond of finding the red glo- 

 bules of the blood to be an oily matter ; and in certain condi- 

 tions these may appear to be inflammable : but a fluid readily, 

 equally, and permanently diffusible in water, cannot be properly 

 considered as an oil. 



" A fourth consideration that leads us to suppose the oil taken 

 in to be intimately mixed with the other parts of the animal 

 fluid, and to make a considerable part in the composition of it, 

 is this, that the oil, which is often copiously laid up in the adi- 

 pose membrane of healthy animals, is again, upon various oc- 

 casions, absorbed and taken into the course of the circulation. 

 Some of these occasions are manifestly those states in which a 

 great degree of acrimony prevails in the mass of blood, as in 

 scorbutic, syphilitic, hectic, and other such cases ; and while it 

 is highly probable that the purpose of such absorption is, by the 



