OP DIGESTION. 371 



3. That at the spot where they empty themselves into the intestine 

 there is frequently a bladder-shaped distension, a kind of -/all 

 bladder (for example, in Lygceus apterus, Cimex baccarum). 



4. That sometimes, as in the secretory organs of other animals, 

 stony concretions are found. 



5. That they are very compact, and wholly surrounded by the fatty 

 substance which is the formative matter whence all secreting organs 

 derive the fundamental portion of their secretion. 



6. That also the vena porta which conducts the blood to the liver in 

 the higher animals takes its rise from such a fatty matter distri- 

 buted within the ventral cavity, viz., from the mesenterium. 



7- That the liver of the most closely allied animals, namely, of the 

 crabs and many annelides (for example, Aphrodites), consists 

 likewise of such blind vascular appendages which empty them- 

 selves into the intestine. 



Whereas these opinions are contradicted by those of modern na- 

 turalists, namely, of Herold, Rengger, Straus Durckheim, Joh. Miiller, 

 and by the altered views of Meckel * and Treviranus f upon the follow- 

 ing accounts : 



1. The biliary vessels empty themselves at a part of the intestine 

 beyond where the chyle has been commenced to be absorbed, 

 frequently closely before the colon, a short distance from the anus. 



2. The chemical analysis of the biliary vessels, and of their con- 

 tents, exhibits but little resemblance between it and the liver, 

 for uric acid is its chief component. According to Chevreul's 

 analysis , the liquid obtained from the biliary vessels was alkaline, 

 and vegetable colours, which had been turned red by acids, it 

 stained blue ; and upon the further addition of acids it precipitated 

 uric acid, and smelt of ammonia when a weak solution of caustic 

 potass was added to it. He thinks, therefore, that this liquid holds 

 urate of potass and ammonia in solution. Wur/er found also 

 urate of ammonia, and both phosphate and carbonate of lime, which 

 Brugnatelli || and John equally found also in the excrement of 

 Lepidoplera immediately after their exclusion from the pupa. 



3. Besides these biliary vessels many insects have other secreting 



* Archiv. fur Anat. u. Phys. Jahrg. 1826. 



f Das organische Lebens neudargestellt, p. 335. + Straus Durk., p. 151. 



Meckel's Arcliiv.,iv. p. 213. || Ib., p. 629. 



B B 2 



