IRREGULAR CELLS IN SPINAL CORD OF FISHES 309 
syncytium, bearing a superficial resemblance at least to the 
giant-cells which occur in certain diseases (as in miliary tuberculo- 
sis) that have been formed by a fusion of many endothelial cells. 
Figure 13 is a low-power microphotograph showing the general 
appearance of a cross-section of flounder spinal cord near the 
posterior end. Six or more of the large Dahlgren cells may 
be seen. The terminal enlargement appears here as a large cap 
on the dorsal side of the spinal cord proper. The central canal 
is located near the ventral side. The horns of gray matter are 
not well defined this far posterior in the spinal cord. In the 
terminal enlargement may also be seen two or three small Dahl- 
gren cells, or pieces of cells. The terminal enlargement is really 
a continuation of the spinal cord (although in this cross-section it 
appears to be separated from it), but it contains practically no 
gray matter. These cells or pieces of cells, therefore, which are 
included in it seem rather out of place. 
As may be seen from the figures, the cells are enormous. In 
actual size a fairly large flounder cell was found to measure 240u 
ventro-dorsally, 160u antero-posteriorly and 110. medio-laterally. 
The average-sized cell is somewhat smaller than this. The 
details of structure of a typical cell may be seen in the cell shown 
in figure 10. The similarities in appearance between this cell 
of the flounder and the one of the skate are evident. The cells 
of the flounder, however, seldom have either vacuoles or granules 
associated with them, at least in appreciable amounts. In some 
cases I have found vacuoles near the edge of a cell containing a 
fine granular, or threadlike, or rod-like precipitate or secretion 
which apparently has been elaborated by the cell. A typical 
one of these is shown in figure 11. Similar thread-like or fine 
granular secretion in vacuoles either inside or outside the cell is 
also often found in the case of the skate cells. In the flounder, 
however, in spite of the huge size of the cells, I have never seen 
any of the large-sized granules similar to those which form such 
a characteristic part of the secretion of the cells of the skate. 
The observations of the cells of the flounder, then, indicate 
that in spite of their enormous size they do not elaborate any 
appreciable amount of granular material, as is the case in the 
