Irving Hardesty - 101 
adult. The series comprises sixteen stages in the growth of the animal. 
Four separate methods are-employed upon each: 1. Fixation in Zenk- 
er’s fluid, thin paraffin sections stained with Ehrlich’s hematoxylin and 
congo red; 2. Zenker’s fluid, paraffin sections, Mallory’s stain for white 
fibrous connective tissue; * 3. Fixation in 10¢ formalin, and prepared by 
the Benda neuroglia method as employed by Huber (loc. cit.) and the 
same as used upon the elephant material; 4. Pieces were fixed in Van 
Gehuchten’s (Carnoy’s) fluid, subjected to continued extraction with 
ether in the Soxhlet apparatus, and digested by pancreatin according to 
the method devised by Flint.” For stages occurring earlier than found 
in embryos of 5 mm. the work of other investigators, chiefly that of 
His, will be accepted and drawn upon. 
The study of this series of preparations is now underway and the 
results obtained will be given in an early paper together with certain 
observations which I now feel sure of being able to add and with illus- 
trations showing the principal phases in the development of the neu- 
roglia fibers. At present it may be said that the study of the develop- 
ing material has so far corroborated with considerable certainty the 
impressions obtained from the adult tissue as to the method by which 
the neuroglia fibers are formed. 
Neuroglia, the chief fibrous supporting tissue of thé central nervous 
system, when compared with the other connective tissues of the body 
is more similar to white fibrous than to any other variety. The re- 
semblance, of course, is a morphological rather than a chemical one, 
and, from the nature of the case, is more apparent in the looser frame- 
works of organs than in the more compact arrangements of white 
fibrous tissue. That neuroglia fibers differ in their chemical properties 
from those of white fibrous tissue is the chief means by which the one 
is distinguished from the other. Like adult neuroglia, white fibrous 
tissue consists of fine fibrils in the meshes of which occur “ cells” either 
in the form of free nuclei or as nuclei with varying amounts of cyto- 
plasm about them. When this cytoplasm is sufficiently abundant it 
usually shows branches, giving the cells either a spindle-shaped or 
irregularly stellate form. Such cells appear to assume the general shape 
of the space they occupy, and the branches of neighboring cells usually 
anastomose through the channels uniting the contiguous cell spaces. 
The fibrils of white fibrous tissue are found, according to locality, either 
as anastomosing bundles or as finer feltworks, varying in arrangement 
14Mallory. Journal of Experimental Medicine, Vol. V, 1901. 
Flint. Johns Hopkins Bulletin, Vol. XIII, Nos. 131-152, 1902. Also Am. Jour. 
of Anatomy, Vol. I, No. 3, 1902. 
