168 NATURAL HISTORY OF WASPS. 
Insect glands, with few exceptions, of which the 
salivary glands of the wasp are perhaps the one most 
familiarly known, are constructed, or, better perhaps, 
are arranged, in a tubular form. The glandular ele- 
ment, consisting here, as in the higher animals, of 
epithelial cells, is placed within the tube, and their 
secretion is poured out from its open end. In the 
particular instance before us, no better or simpler 
means to gain the object in view, under all the circum- 
stances, could be devised. The long capillary tubes 
float free, by the side of the tracheze in the fluid on 
which they are designed to act, and the products of 
their operations are poured directly into the alimentary 
canal. Much of the ordinary glandular system, and 
the whole lymphatic system are thus dispensed with 
in the wasp’s economy. 
By very careful manipulation, with the forceps and 
dissecting needle, this tangled mass of gland tubes 
and traches may be removed, leaving the small intes- 
tine quite clear, as a tube of much smaller calibre and 
much less strength than, though otherwise bearing a 
general resemblance to, the stomach. It lies deep, at 
the back of the abdominal cavity, behind the left 
ovary, carrying the spiral coil which we have been 
tracing still farther downwards and to the left. It is 
separated from the next following section, the colon, 
by a line of demarcation yet more distinct than that 
which separates it from the stomach. Thus ;—-it con- 
tracts rapidly to a narrow point, which indents the 
though the food happened to be the same as in the instances where I 
had found it present. It was absent from the contents of the distended 
colon of Ligurian bees dying of an epidemic disease. It was present 
in large quantity in the excretions of a leaf-cutter bee. 
