AUTHOR’S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, APRIL 17 
FURTHER COMPARATIVE STUDIES IN OTHER FISHES 
OF CELLS THAT ARE HOMOLOGOUS TO THE LARGE 
IRREGULAR GLANDULAR CELLS IN THE SPINAL 
CORD OF THE SKATES 
CARL CASKEY SPEIDEL 
Department of Anatomy, University of Virginia 
TWO PLATES (THIRTEEN FIGURES) 
INTRODUCTION 
It was pointed out by Dahlgren (1) that there exists in the 
spinal cord of the skate a series of large remarkable cells of 
peculiar structure. The complete morphology, location, and 
distribution of these cells together with some experimental 
results have been published by the writer in a previous paper. 
(2). This present paper deals especially with the occurrence and 
appearance in other fishes of cells homologous to these cells of 
Dahlgren. 
In the skate, Raia, the cells are present in the anterior horn 
of gray matter on each side of the central canal, their exact 
position, however, being rather variable. They are located in 
the posterior portion of the spinal cord only, being placed in 
Raia ocellata in the posterior half of the tail (i.e., extending from 
the level of the sixty-fourth vertebra to the tip of the tail, ap- 
proximately the one hundred and twentieth vertebra). 
The cells are of enormous size, a large one that was measured 
being about 300u long (antero-posterior measurement), 200u 
wide (medio-lateral measurement) and 176u thick (ventro-dorsal 
measurement). At first sight of one it is difficult to believe that 
it is a single cell (fig. 9). It is irregular in outline and contains 
a huge nucleus of the distributed, branching type extending to 
all parts of the cell. In sections this often appears to be multiple 
in character, causing the cell to resemble a fusion of a number of 
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