22 Papers from the Department of Marine Biology. 
PILOCARPINE STIMULATION OF THE SPINAL CORD. 
Method.—The spinal cord was laid bare slightly anterior to the first 
tail-fin. The tip of the tail was then cut off about an inch from the 
posterior end and a solution of pilocarpine (0.1 per cent) injected into 
the vertebral canal. The posterior portion of the spinal cord was thus 
bathed in the pilocarpine solution, and it is probable that a certain 
amount of the drug entered the blood-stream by way of the spinal vein 
that lies directly upon the cord. From each of the skates treated in 
this way three pieces of the spinal cord were taken in the same way as 
was done in the experiments with electrical stimulation. These pieces 
were fixed in Bouin’s fluid and the sections stained in iron hematoxylin 
and van Gieson’s stain. The skates of the first series of experiments 
were collected in August, those of the second series in May. 
First SERIgs. 
Skate 75: Stimulated for 5 minutes. Huge vacuoles present (fig. 20). Many granules are 
in evidence. In some cases the cell cytoplasm is filled with granules. The cells appear 
to be in a high state of activity. 
Skate 76: Stimulated for 10 minutes. Many granules present. Especially noticeable is 
the close association of granules and cells. Figure 21 shows one of the large cells on one 
side of the central canal. Many granules are in this region, while on the other side of 
the central canal there is not a single granule, the reason seeming to be that there are 
none of the large cells near by. 
Skate 77: Stimulated for 20 minutes. Some granules present, but not so many as in the 
case of the two preceding skates. No vacuolation of the cytoplasm of the cells could 
be noticed. 
SEconpD SERIEs. 
Skate 111: Stimulated for 2 minutes. Skate 142: Stimulated for 5 minutes. 
Skate 112: Stimulated for 2 minutes. Skate 109: Stimulated for 10 minutes. 
Skate 107: Stimulated for 5 minutes. Skate 110: Stimulated for 10 minutes. 
Skate 108: Stimulated for 5 minutes. Skate 142: Stimulated for 10 minutes. 
From an examination of the three skates of the first series of experi- 
ments it was concluded that pilocarpine stimulation of the spinal cord 
caused a very definite increase in the amount of granular material. 
The average amount of granular material per section in terms of unit 
granules was computed in the case of each skate, just as was done in the 
case of the skates stimulated with electricity. The skate stimulated 
for 5 minutes showed an average of 7.5 unit granules per section. The 
skate stimulated for 10 minutes averaged 28.3 unit granules per sec- 
tion. The skate stimulated for 20 minutes showed an average of 10.6. 
The average of the 12 normal control animals was 10.7. The first 2 
skates of this series, therefore, show a remarkable increase in amount of 
granular material. The third skate is about normal. It was thought, 
however, that much of the apparent increase in granular material 
might be due merely to genetic variation; that in the animals used for 
this experiment there had chanced to be more than the average amount 
of granular material to start with. The second series of pilocarpine 
experiments showed that this was undoubtedly the case. In these 
