THE NEUROGLIA OF THE SPINAL CORD OF THE ELEPHANT 
WITH SOME PRELIMINARY OBSERVATIONS UPON THE 
DEVELOPMENT OF NEUROGLIA FIBERS. 
BY ; 
IRVING HARDESTY. 
From the Hearst Anatomical Laboratory, University of California. 
With 4 Text FIGuREs. 
The material from which is made the following contribution to the 
comparative study of neuroglia has been on hand several years. It 
consists of a portion of the spinal cord of a 21-year old bull elephant 
killed in Bridgeport, Conn., in 1897. Through the kindness of Prof. 
H. H. Donaldson, the specimen was finally allotted to me and a partial 
description of its gross and microscopic anatomy is contained in a pre- 
vious paper. The material was removed a few hours after death and 
fixed in 10¢ formalin in which the unused portions have been preserved 
ever since. 
The medullated axones of the spinal cord of the elephant have an 
appreciably larger diameter than those of man or of any of the mam- 
mals more usually studied. Measurements, inclusive of the medullary 
sheaths, of fifty axones in an average field of a transverse section of the 
cervical region stained by the Weigert hematoxylin method give diame- 
ters ranging between 25 y» and 8 w with an average diameter of 19 y. 
Similar measurements from the human specimen, prepared in the same 
way, give diameters varying from 17 » to 6 » with an average of about 
11 yw. The larger axones of the spinal cord of the elephant result, of 
course, in larger inter-axone spaces. These larger spaces being occupied 
by the neuroglia allow, in consequence, larger areas for its study. This 
fact suggested the spinal cord of the elephant as a favorable field for the 
study of the neuroglia cells in that larger areas in the vicinty of the 
neuroglia nuclei were to be expected. 
The study has been suggestive of several conclusions, the validity 
of which must be further tested by recourse to developing material. 
Aside from these, however, the tissue in itself may be of interest. 
1 Hardesty. Observations on the Medulla Spinalis of the Elephant, with some 
Comparative Studies of the Intumescentia Cervicalis and the Neurones of the Col- 
umna Anterior. Jour. Comp. Neurology, Vol. XII, No. 2, 1902. 
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