254 



STETJCTUEE OF GLA1STDS. 



members. The blind extremities of the glands are surrounded 

 immediately by the blood, which is poured freely into all the 

 interstices of the body, and so attract the substances from its 

 mass which the glands of other and higher animals have 

 brought to them by finely divided capillary reticulations, to be 

 subjected to their peculiar elective attractions. 



[ 420*. It is infinitely more difficult to form an idea of the 

 glandular skeleton of man and the vertebrata, in the fully 

 formed condition, the composition of this being much ob- 

 scured by the connecting cellular tissue and intermingled net- 

 works of vessels. Still there are cases even here, where, 

 without peculiar difficulty, the two principal types in glandu- 

 lar architecture may be seized. As examples, the Harderian 

 glands of birds generally (fig. 255), and the Cowper's glands 

 of the hedgehog (fig. 256) may be quoted. Into both struc- 

 tures a quicksilver injection flows readily, and renders the 

 arrangement of their parts perfectly distinct even to the naked 

 eye. The gland of Harder of the pelican (fig. 255) is seen 

 as a considerable lobulated body, each lobe being subdivided 

 into smaller rounded or elongated or angular lobules, which 

 again present themselves as small hollow pannicles or berries, 



Fig. 255. A, a Harderian gland of the Pelecanus onocrotahis, with the 

 excretory duct of the natural size injected with mercury. B, a portion 01 

 the same slightly magnified. Some vascular ramifications are still appa- 

 rent between the lobules. 



