24 
Papers from the Department of Marine Biology. 
DISCUSSION OF RESULTS FROM SPINAL-CORD STIMULATION. 
The results from the preceding experiments may be summed up in 
the statement that electrical and pilocarpine stimulation cause definite 
increase in the amount of granular material, while treatment with atro- 
pine has no effect. Text-figure 3 indicates the 
granular material present in the normal animals 
and in those stimulated by each of the methods 
used. 
These results afford further evidence that the 
large cells are gland-cells. Pilocarpine is a spe- 
cific gland stimulant, and electrical stimulation 
is ordinarily though not invariably followed by 
increased secretion. Atropine inhibits glandular 
activity. No marked decrease in the amount of 
granular material was noted in the skates stim- 
ulated by atropine, but this is believed to be due 
to the slowness with which the granules already 
present in the cord are absorbed by the blood- 
stream. It has already been pointed out that 
these granules are not very readily soluble, and 
in the spinal cord they evidently must persist 
for some time. 
The number of animals used in these experi- 
ments is not very large: 17 for electrical stimu- 
lation, 11 for pilocarpine stimulation, 9 for atro- 
pine stimulation, and 12 as control animals. 
relative amounts of 
atro. 
pilo. 
elec. 
norm. 
OSS. 110) Wis 20) 625 
Unit granules 
TEXT-FIGURE 3.— Dia- 
gram showing the com- 
bined results from electri- 
cal, pilocarpine, and atro- 
pine stimulation, and how 
they compare with the nor- 
mal average amount of 
granular material present 
in unstimulated skates. 
The abscisse represent the 
average number of unit 
granules per section. The 
average number of unit 
granules per section from 
the normal and atropine 
stimulated animals is about 
the same. The average 
from the pilocarpine and 
electrically stimulated ani- 
é i 5 mals is much greater. 
However, if the number of cells examined is 
taken into account, it will be seen that the results are based upon 
large numbers of cases. It is the cell and not the entire animal 
that is the real unit of variation in these experiments. The number 
of sections examined from the electrically stimulated skates was 
6,716. As the gland-cells occur 1 about every 30 sections in the regions 
of the spinal cord examined, this number of sections would include 
224 cells. The results from the skates stimulated by pilocarpine 
are based upon examination of 6,472 sections, or about 216 cells. 
The results from atropine-stimulated skates are based upon exam- 
ination of 4,660 sections, or 155 cells, and the results from the con- 
trol animals upon 7,144 sections, or 238 cells. The number of cases, 
therefore, is large enough to give good averages with no great devia- 
tions due to a few chance variations. 
The method of estimating the volume of granular material in any 
section is admittedly not an exact one. Only approximately could it 
be calculated how many unit granules were equivalent to the amount of 
granular material present in any section. No better method, however, 
could be devised. 
