104 INTERNAL ANATOMY OF INSECTS. 
Cuvier thinks their texture is spongy*. ‘They appear 
to contain a number of small, irregular, dark granules, 
which float in a peculiar fluid, with which, however, they 
are not always filled throughout, nor are they constantly 
permeable from one end to the other. Thus, in the meal- 
worm beetle (Tenebrio Molitor), the common trunk by 
which they are attached to the intestinal canal is com- 
posed of gelatinous granules®. The place of their in- 
sertion is generally a little below the pylorus, but in the 
common cockroach they are inserted into the stomach 
just above that part®. Usually each vessel opens singly 
into the intestinal canal, which the whole number sur- 
round at an equal distance from each other’. Some- 
times, however, they are connected with it by a common 
tube in which they all unite, as in the asparagus-beetle 
(Lema Asparag?*); in the house-fly (Musca domestica), and 
other Muscidc, each pair unites so as to form a single 
branch on each side of the canal previously to their in- 
sertion f ; in the field-cricket (Gryllus campestris) they are 
all inserted in one spot®: and when numerous, they are ge- 
nerally attached singly though irregularly’. These ves- 
sels at their base do not open into the cavity of the in- 
testinal canal, but merely into the space between its outer 
and inner tunicks, the last being constantly imperforate. 
With regard to their apex, the bile-vessels are some- 
times fixed singly or connectedly to the intestine merely by 
a few muscular fibres; for they do not enter it, their ends - 
having no orifice. This structure is mostly to be met 
® Ubi supr. » Ramdohr, uz supr. * Ibid. 44. t. if. 9. 
a Tbid. e Tbid. t. wiay.i6s A. 
o That Kia f, eV Os 22 PsP. O, @ Lbwst. Vfl okhhe 
h Jbid. t. xin. f. I—3, i Ibid, 44. 
