96 The Neurogha of the Spinal Cord of the Elephant 
rations reveals the fact that the nuclei of the eosinophiles and of the 
polymorphonuclear varieties generally stain very lightly or not at all 
by the Benda neuroglia method. ‘The cells in question having a single 
nucleus with even contour and a relatively small amount of cytoplasm, 
must be considered as lymphocytes. Outside the blood-vessels this va- 
riety of cell may be found in all conceivable positions among the nerve 
fibers and often without reference to the amount of space. Usually its 
nucleus is spherical but when pressed between other structures it may 
be rod-shaped. ‘There is reason therefore for considering these cells as 
other than neuroglia cells. They are looked upon as small mononuclear 
lymphocytes which, outside the blood-vessels, may be called “ wander- 
ing cells.” 
5. Most of the neuroglia nuclei appear free from cytoplasm. These 
free nuclei vary greatly in size, ranging from the truly vesicular type 
with a diameter equal to those possessing cytoplasm, through the va- 
rious degrees of compactness and density in staining, to a type with a 
diameter of 4 ~ and less. In general it may be said that the smaller 
the nucleus the more compact is its chromatin and therefore the more 
deeply does it stain. None of the more deeply-staining nuclei ever 
have a vestige of cytoplasm about them. The free nuclei are generally 
spherical or oval in the elephant but may be polymorphic. They vary 
in size from 15 # to 3 yw in diameter and the smallest always stain as 
one compact mass. All transition forms may be observed between the 
smallest and the large vesicular type, suggesting that the one may be 
derived from the other. What are considered some of these stages of 
transition are shown in Figures 3 and 4. The nuclei e to h taken in 
their order illustrate the diminution in size accompanied by the in- 
creased density in staining. 
6. Now and then a nucleus of the smallest type may be noted which 
appears as though in the process of disintegration. All the stages of 
karyolysis usually described for other tissues have not been observed 
in these nuclei, and little more can be said of them than that the com- 
pact chromatin seems to undergo fragmentation and occurs as a small 
jagged mass either in the center of the nucleus or more often at one 
side of its outline (i, Figs. 3 and 4), while the rest of the nuclear area 
appears practically clear. Nuclei which may be considered as belong- 
ing to this type are by no means so numerous as the other types of free 
nuclei. They occur at the rate of about one in every two fields under 
the oil immersion. They are generally under 4 ~ in diameter. They 
sometimes resemble the transverse sections of the smaller axones and 
but for the deep stain and the absence of the structures belonging to 
