INSECTS. 257 



physiological, and would never have been entertained but for the 

 attempt to reconcile two conflicting views, and which ought always 

 to be distrusted when it interferes with more extended enquiry. 

 But if we suppose an organ answering to the liver to be alto- 

 gether wanting in insects, then it must be proved that the separa- 

 tion of bile is more important in the animal economy than the 

 excretion of urea, before an argument can be borrowed therefrom 

 against the function ascribed to the Malpighian vessels. We do 

 not forget that by respiration and the elaboration of bile the 

 quantity of carbon in the living body is diminished, and that from 

 be large development of the respiratory organs in insects the 

 xcretory office of the liver is in a great measure dropped *, 

 sTevertheless it is still highly probable that parts, whose function 

 grees with that of a liver, are not altogether absent in Insects, 

 n the first place we might here refer to the great quantity of 

 it the adipose body situated between the skin and the intes- 

 ne, which invests every organ and is of very great extent, more 

 specially in larvae whose respiration is less perfect; the carbon 

 nd hydrogen which in other instances is combined with oxygen to 

 uit the body by respiration, here forms that provision of com- 

 ustible matter so necessary in the animal economy for the support 

 f respiration, especially in the case of Insects, which as Nymphs 

 ike scarcely any food. Since then this production of fat exerts 

 le same influence on the composition of the fluids as the separa- 

 xm of bile, it is not to be considered as a proceeding entirely 

 rbitraiy if some recognise in the adipose body an analogon of 

 liver 2 . The adipose body consists of a multitude of minute 

 acs or vesicles bound together by air-tubes which spread them- 

 slves as a fine network on their surface. In the second place, coecal 

 ppendages are seen below the muscular stomach in the Orthoptere 

 sight in Mantis, six in Gryllus, two in Acketa) which involuntarily 

 all to mind the appendices pyloricce of osseous fishes : they pro- 

 ably secrete a fluid that performs the office of the bile in diges- 

 lon 3 . In other insects, finally, as in the Carabici among the 



1 CURMEISTEB ffandb. der Entomol. I. p. 403. 



2 OKEN Lehrb. der Naturphilosophie, in. 1811, s. 270 ($tte Auflage, s. 425). 



s That these blind appendages arise from an immediate extension (protrusion) of the 

 itestinal canal is no proof, as LEON DUFOUK supposes, that they cannot be secretory 

 VOL. I. 17 



