Gland-Cells of Internal Secretion in Spinal Cord of Skates. 13 
special interest for comparison with these large cells of the skate. The 
following brief but excellent description has been taken, with a few 
omissions and modifications, from “The Endocrine Organs,” by 
K. A. Schaefer: 
Like most of the other special endocrine organs, it is found with very few 
exceptions in all vertebrates. It is connected with the floor of the third ven- 
tricle by a short hollow stalk, the infundibulum. This stalk is composed of 
nervous tissue and expands into the interior of the gland into what is known as 
the pars nervosa, which when examined by appropriate methods is found to be 
mainly composed of neuroglia fibers and cells. In some animals the cavity of 
the infundibulum with its lining of ependyma is prolonged in the form of a 
blind canal far into the pars nervosa, but in man this canal has become oblit- 
erated, although it existed in the early embryo. 
In front of and partly surrounding the pars nervosa the organ is formed of a 
mass of epithelial cells granular in appearance. This constitutes the pars 
anteriosa seu glandularis. It is highly vascular. In the middle of the organ 
the pars anteriosa is separated from the pars nervosa by a cleft lined by 
columnar, cubical, or flattened epithelial cells and filled with a glairy fluid. 
The pars intermedia is a layer of epithelial tissue lying between the pars 
nervosa and this intraglandular cleft, not so granular and vascular. 
Pars antertosa. The cells are (1) clear, non-staining (chromophobe), and 
(2) granular, staining (chromophil); and the granular cells are again divisible 
into oxyphil and basiphil, the oxyphil cells being by far the most numerous. 
In some animals, notably elasmobranch fishes such as the skate, all of the 
cells of the pars anterior are set like a columnar epithelium around blood 
sinuses. Most of the cells also contain numerous fine fatty globules. There 
is a small amount of reticular connective tissue between the cells. A few 
nerves have been traced into the pars anterior from the pars nervosa. In 
some cases vesicles containing colloid may be present. 
Pars intermedia. The cells contain fine neurophil granules. Often they 
surround well-defined vesicles containing oxyphil colloid. In addition to these 
colloid masses, some of the cells of the pars intermedia may often be seen 
in different stages of conversion into globular hyaline bodies, their proto- 
plasm and nucleus becoming swollen; the latter may have become indistinct or 
have disappeared. Some of the globules thus produced are granular in char- 
acter rather than hyaline. In both cases the cells ultimately break down, 
setting free the hyaline or granular substance. The pars intermedia is by no 
means everywhere marked off from the pars nervosa, for strands of the cells of 
the pars intermedia may extend a variable distance between the fibers of the 
pars nervosa. The hyaline and granular globules which have been derived 
from its cells also pass into the substance of the pars nervosa and are seen 
between its fibers; they can in fact be traced as far as the continuation of the 
third ventricle into the stalk. This fact was pointed out by Herring, who 
concluded that the hyaline and granular substances which are produced by 
conversion and breaking down of the cells of the pars intermedia form the 
secretion of this portion of the pituitary and that this secretion passes into the 
cerebro-spinal fluid. In confirmation of Herring’s conclusion, evidence that 
the active principle of the posterior lobe of the pituitary is present in cerebro- 
spinal fluid has been obtained by Cushing and Goetsch, although their results 
have been traversed by Carlson. It has, however, been shown by Cow that 
intravenous administration of duodenal extract indubitably causes the appear- 
ance of the pituitary autacoids in the cerebro-spinal fluid, a fact which makes 
it evident that they must normally be passed to some degree into that fluid. 
