360 ADOLPH R. RINGOEN 
In order to elucidate more clearly the sequence of events that 
takes place in the evolution of a selachian gland from the simple 
tubular condition on through to the typical flask-shaped form, 
it has seemed feasible to submit a number of diagrams illustra- 
tive of the rotation processes. A casual reference to these 
diagrams will enable one to comprehend at a glance, without 
the aid of detailed figures and descriptions, that an actual rota- 
tion of cells play a fundamental rdle in molding the fundiec por- 
tion of the Selachian gastric gland. 
In figure 1, diagram A, the glandular outgrowth has extended 
only a short distance, and in most instances the long axes of 
the nuclei are parallel to the long axes of the outgrowth. This 
is the condition one would expect to find, since in a slightly 
younger stage (fig. 3) the nuclei are also parallel to the long axes 
of the gland rudiment. Diagram 1B shows that the glandular 
outgrowth has not only increased in length, but that a number 
of the nuclei are beginning to change their long axes with ref- 
erence to the long axes of the outgrowth. With reference 
to these shifting movements Scammon (715) states “that it 
is hardly to be considered that the nuclei shift their axes within 
the cells.’’ Since cell boundaries were not seen in the speci- 
men, illustrated in figure 1B, it may be reasonably assumed 
that the shifting movements of the nuclei are but the shifting 
movements of the cells which contain them. The next diagram 
(fig. 1C) distinctly shows that the cells in the region of what is 
to form the future fundice portion of the gland have rotated 
through an angle of about 90°. It is very probable that the 
cells located at. what may be called the center of the base of 
the fundus do not change their positions, since their nuclei 
show no shifting movements at any time. Diagram 1D shows 
that all of the nuclei have passed through a change in their 
original axes of about 90°. The long axes of the nuclei now 
lie at right angles to the lumen of the gland. In figure 7 the 
outlines of the cells were drawn just as they appeared in the 
actual specimen. This shows that the rotation of the nuclei 
is to be interpreted only as the shifting movements of the cells 
that contain them. 
