LETTERS. 607 



did these vessels carry chyle, they could not always (which 

 nevertheless they do) contain a white fluid in their interior, 

 but would sometimes be coloured yellow, green, or of some 

 other hue (in the same way ' as the urine is affected, and 

 acquires different colours from eating rhubarb, asparagus, figs, 

 &c.) ; or otherwise, when large quantities of mineral water were 

 drunk, they would be deprived of almost all colour. Besides, 

 did that white matter pass from the intestines into those 

 canals, or were it attracted from the intestines, the same fluid 

 ought certainly to be discovered somewhere within the intes- 

 tines themselves, or in their spongy tunics ; for it does not 

 seem probable that any fluid by bare and rapid percolation of 

 the intestines could assume a new nature, and be changed into 

 milk. Moreover, were the chyle only filtere"d through the 

 tunics of the intestines, it ought surely to retain some traces 

 of its original nature, and resemble in colour and smell the 

 fluid contained in the intestines ; it ought to smell offen- 

 sively at least ; for whatever is contained in the intestines is 

 tinged with bile, and smells unpleasantly. Some have conse- 

 quently thought that the body was nourished by means of 

 chyle raised into attenuated vapour, because vapours exhaling 

 in the alembic, even from fetid matters, often do not smell 

 amiss. 



The learned Pecquet ascribes the motion of this milky fluid 

 to respiration. For my own part, though strongly tempted to 

 do otherwise, I shall say nothing upon this topic until we are 

 agreed as to what the fluid is. But were we to concede 

 the point (which Pecquet takes for granted without any suf- 

 ficient reason in the shape of argument), that chyle was con- 

 tinually transported by the canals in question from the intes- 

 tines to the subclavian veins, in which the vessels he has lately 

 discovered terminate, we should have to say that the chyle be- 

 fore reaching the heart was mixed with the blood which is about 

 to enter the right side of the organ, and that it there obtains 

 a further concoction. But what, some one might with as good 

 reason ask, should hinder it from passing into the porta, then 

 into the liver, and thence into the cava, in conformity with 

 the arrangement which Aselli and others are said to have 

 found ? Why, indeed, should we not as well believe that the 

 chyle enters the mouths of the mesenteric veins, and in this 



