28 E. V. COWDRY 
My contention regarding oscillation in secretion in the thyroid 
receives some support from a study of the parathyroid glands in 
which the reticular material has only thus far been recorded by 
Kolmer (17, p. 272).!. He illustrates it in the form of a rather 
dense and well-circumscribed network of a ring-like shape. Since 
he finds that it is located at one pole of the nucleus (as in colum- 
nar epithelia), he concludes that the cells possess two poles and 
are cylindrical in shape, not roughly cubical as is generally sup- 
posed to be the case, and, further, that they are disposed in rows 
or end to end. My preparations of the parathyroid glands of 
guinea-pigs reveal a blackened network which is usually some- 
what more diffuse (figs. 10, 11, and 12). Quite frequently it is 
cirecumnuclear in position, as is illustrated in one cell in figure 12. 
But when the cells become grouped, the reticular material comes 
to occupy a position between the nucleus and what may be con- 
sidered to be the discharging pole. This condition is evident in 
rare cases when the cells form follicle-like cavities, as shown in 
particular by figure 138. The arrangement of cells in figure 12 
is also suggestive. From this we may conclude that here also 
the reticular material acts as an indicator of polarity assumed 
under normal but unknown conditions. 
Special interest attaches to the parathyroid glands because 
their secretion is active, but unknown, and because true secretion 
antecedents remain to be discovered within their cells. Perhaps 
they may be more easily detected in these cells which assume a 
certain measure of polarity, though it would be unsafe to say 
that cells not definitely grouped are any lessactive physiologically. 
The same amount of secretion antecedent in a polarized cell is 
condensed into a relatively small area of the cytoplasm, whereas 
in an unpolarized cell it is presumably spread throughout a much 
larger extent of peripheral cytoplasm for transport in all direc- 
tions. Just as in the thyroid, the first clues will probably be 
found in hyperactive glands (if such can be produced). But we 
have to remember that under normal conditions the secretion 
antecedents may be present in such minute amounts or may be 
1 Kolmer (’16, p. 507) also mentions the reticular material in the thyroid 
gland, but does not describe its position within the cell. 
