PHARYNGEAL GLAND OF THE EARTHWORM 4] 
As to the histological structure of the pharyngeal bulb, we 
shall, for the sake of clearness, examine separately the structure 
of its three portions: (a) the deep glandular portion, (b) the 
conductive or musculo-vascular portion, and (c) the superficial 
or epithelial portion. 
(a) The deep or glandular portion. 
The deep or glandular portion of the pharyngeal bulb is 
composed of a certain number of lobules of various sizes, 
suspended in the coelomic cavity of the earthworm and extend- 
ing backwards as far as the fifth or the sixth segment of the body 
(Text-figs. 1 and 2, s. gl.). These lobules, as well as the entire 
bulb, are surrounded by a thin peritoneal membrane (‘ capsule ’ 
of Stephenson) composed of flattened cells with elongated 
nuclei. The peritoneal membrane penetrates between the 
lobules, and in some places into the lobules, especially where the 
latter are traversed by muscular bundles, or by the blood-vessels, 
which are directed forwards and ramify in, and form the main 
part of, the musculo-vascular portion of the bulb (Text-figs. 
1 and 2, c. m. v.). 
The cells which compose the glandular lobules are very poly- 
morphic, being either spherical or elongated, or even semilunar. 
Sections derived from well-fixed material (in Champy’s fixative, 
for instance) do not show clearly the boundaries between the 
cells, while on the other hand, a less perfect fixation, which 
slightly contracts the cells, defines their contours, and demon- 
strates that, m some places, the protoplasm of these cells is con- 
tinuous. The size of these cells varies as much as their form ; 
in Allolobophora chlorotica, for instance, they are 
from 20» to 30” long and 18 wide. Each cell contains a 
large spherical nucleus of 7-8 in diameter which is provided 
with a large nucleolus of 83-4 in diameter (PI. 3, fig. 4, m. gl.). 
The peripheral chromatin of the nucleus is generally much 
reduced, but its quantity seems to depend upon the activity of 
the cells. The protoplasm, as was shown by Stephenson, is 
very basophile, for which reason he called these cells ‘ chromo- 
phile’. When stained by Haemalum, tron Haematoxylin, or 
