OP DIGESTION. 375 



the intestine in animals which admit of being compared with the 

 biliary vessels, unless it be precisely the same forms in the Annelides 

 and Crustacea. These have been, particularly in the Crustacea, ex- 

 plained as the liver, and therefore the biliary vessels must be consi- 

 dered as the analogues of these filaments, or at least, as the analogues 

 of the liver. With respect to form, this is doubtlessly correct, the above 

 cited reasons speak too clearly in favour of it ; but in function they 

 are not merely liver, indeed not purely secreting organs but more 

 justly excretory organs, which, however, do not separate urine alone, 

 but also a kind of gall, and only in those instances where true urinary 

 organs are wanting undertake as well the function of urinary organs. 

 With respect to what may be objected from their opening higher 

 into the intestinal canal, we may reply, that probably the whole re- 

 maining portion of the intestinal canal absorbs but little chyle, but 

 instead, as Joh. Muller also considers, leads off the unassimilating 

 remains. But in those instances where there are actual urinary 

 organs the biliary vessels may be exclusively liver, at least their 

 darker brown red colour in all these cases speaks in favour of it, par- 

 ticularly in the Carabodea and Dylici. In these then the tolerably 

 long and especially broad and muscular ilium must also separate chyle. 



I therefore positively consider the biliary vessels as analogues in 

 form of the liver, but which do not exclusively exercise the function 

 of the liver, but conjunctively, at least in many cases, the function of 

 the kidneys, and of other secreting organs. 



An opinion propounded by Oken explains the fatty substance as 

 liver, but it is inapplicable, as has been shown by Meckel. Yet we 

 cannot deny that the fatty substance has some relation to the liver, 

 for the organisation of the Arachnids speaks distinctly in support of 

 it. The biliary vessels may also, when they secrete bile, derive the 

 foundation of their excretion from the fatty substance only, and we 

 therefore find them everywhere closely enveloped by this fatty sub- 

 stance. 



With respect to the direct observations of some physiologists, besides 

 those already cited, upon the function of the biliary vessels, we find, 

 according to Rengger, that they contain a clear fluid, in which the mi- 

 croscope detects a great number of globules. This fluid appeared more 

 transparent and brighter when watery substances were received into the 

 intestinal canal, and he therefore supposes that it is the water separated 

 from the blood. He then observed the fluid, upon pressing the vessels, 



