20 Papers from the Department of Marine Biology. 
in chloroform, and some in ether. After 24 hours the pieces were 
prepared for microscopic study to see whether the granules had been 
dissolved. Inall cases a normal amount of granular material was pres- 
ent. Sections of the spinal cord from alcohol fixation were treated 
with a few acids and alkalies. The granules were found to be dissolved 
by nitric acid—not, however, by potassium hydroxide, sulphuric acid, or 
weak hydrochloric acid. 
ELECTRICAL STIMULATION OF THE SPINAL CORD. 
Experimental work was now undertaken to test, if possible, the 
hypothesis that these large cells of the skate were gland-cells. If the 
granules were being secreted by the cells, it was considered probable 
that electrical stimulation of the spinal cord would be followed by an 
increase in the amount of granular material. 
Method.—In all of the following experiments the spinal cord was laid 
bare slightly anterior to the first tail-fin. Platinum electrodes, which 
led off from an induction coil attached to a single dry battery, were 
applied directly to the spinal cord. After stimuli had been sent in for 
the desired length of time, pieces of spinal cord were taken; one slightly 
posterior to the point of stimulation, one 2 inches posterior to the point 
of stimulation, and one about 4 inches posterior to the point of stimu- 
lation. These pieces were fixed in Bouin’s fluid. Sections were cut 7 
to 8 microns thick and stained with iron hematoxylin and van Gieson’s 
stain. Skates of the species Raia ocellata were used, those of about the 
same size being selected. The first series of skates was collected in 
August, the second series in May. 
First SERIES OF SKATES. 
Skate 40: Stimulated for 2 minutes, fixed immediately. The cytoplasm of some of the cells 
showed disintegration and liquefaction, especially at the periphery. A few granules 
were present. 
Skate 83: Stimulated for 2 minutes, fixed immediately. Very small granules are present. 
Vacuoles are present outside the cell filled with secretion. 
Skate 41: Stimulated for 2 minutes, fixed 5 minutes later. Very small granules are present. 
Skate 84: Stimulated for 5 minutes, fixed immediately. Granules are not present in very 
large amounts. Chromatic granules are often drawn out in strings as if movement has 
occurred. 
Skate 44: Stimulated for 5 minutes, fixed 10 minutes later. Many granules are present. 
The nuclear material is usually arranged around the periphery of the cell. In figure 24 is 
shown a case where the ependymal cells of the central canal have been pushed aside by 
one of the cell processes. Reissner’s fiber, which is ordinarily inside the central canal, 
is here entirely inclosed by the cytoplasm of the cell process. 
Skate 26: Stimulated for 5 minutes, fixed 25 minutes later. Many granules of various 
sizes present, often being arranged in lines. 
Skate 85: Stimulated for 10 minutes, fixed immediately. Granules present in rather large 
amounts. 
Skate 86: Stimulated for 10 minutes, fixed 10 minutes later. Many granules present. 
Skate 48: Stimulated for 10 minutes, fixed 30 minutes later. Many granules present. 
Skate 49: Stimulated for 20 minutes, fixed 15 minutes later. Many granules present. 
Skate 50: Normal animal that had been kept in the same environment as the animals that 
were subjected to the electrical stimulation. Comparatively few granules present. 
