364 PHYSIOLOGY. 



a thick pappy mass, which melts by the addition of acid, and on the 

 applicatipn of heat, it is found in the blind appendages as well as 

 in the cavity of the canal. It is of a white colour, and is thereby 

 distinguished from the brown nutriment found in the crop. Ramdohr 

 and the earlier entomotomists call this division of the intestine, behind 

 which the biliary vessels open themselves, the stomach ; according to 

 Treviranus, Joh. Muller, and Straus Durckheim *, on the contrary, it 

 should be called duodenum f. This last opinion is doubtlessly the 

 most correct, for the Avhole business of chymifaction is already over 

 when the food arrives at this portion of the intestine, and the formation 

 of chyle commences here. The resemblance of the crop to the anterior 

 stomach, and the proventricnlus to the muscular stomach of birds, is so 

 striking, that the similar situation of that portion of the intestine behind 

 the muscular stomach would oblige us to consider both as analogous 

 forms, even were all other resemblances wanting. The chief difference 

 however is, that the biliary ducts do not, as in the birds, open into this 

 division, but behind it ; but in lieu of which other secreting organs, 

 which are the equivalents of the pancreas, namely, the blind append- 

 ages, are found around its entire circumference. Rengger does not 

 consider these appendages as secretory organs, but as pockets, whence 

 the lacteal juice is more readily passed into the ventral cavity, and 

 because chyme is also found in them ; but that is also found in the 

 pyloric caecum of fishes. Their abbreviation, however, upon the filling 

 of the intestine, is not an objection, but it merely proceeds from the 

 necessary distension of the intestine produced by the accumulation 

 of more matter. Another reason, however, for not considering that 

 division of the intestinal canal lying behind the proventriculus as the 

 stomach, is the deficiency of a peculiar nerve in its vicinity. The 

 nervus sympathicus descends, we know, from the brain to the pharynx, 

 and distributes itself upon the surface of the crop, with several branches 

 and ganglia, similar to the web of the superior animals. But if there 

 be a proventriculus the branches of the nerves suddenly cease in 

 its vicinity, and that portion of the intestine lying behind the pro- 

 ventriculus receives none ; but where the proventriculus is wanting the 

 nerves are distributed only at the anterior portion of the stomach, and 

 the posterior part which corresponds with the duodenum receives none 



* See above, 105. 



j- The true duodenum of insects is the villose stomach, or, where this is wanting, the 

 lonj tubular stomach itself. 



