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young animals, he doubted the cell-nature of the bodies seen in the 
same position in the adult brain. 
WIEDERSHEIM (’90), while examining living animals, discovered 
movements in the brain in this same region and was led to believe 
that certain parts of the brain were not in a fixed condition. 
Samassa (91), in a short article, showed that these movements 
were those of inclusions in the giant cells of the brain. Finally, 
after more careful investigation, he (’91) confirmed his previous 
statements concerning the giant cells and described the optic ganglion 
and brain in more detail. He was the first investigator, probably, to 
thoroughly study sections of the brain and optic ganglion, though 
Carrtmre (’85), several years earlier, published a drawing of a longitu- 
dinal section of the eye and optic ganglion. 
My own investigation was begun in the early fall of 1895 at 
the suggestion of Prof. E. A. Biren, of the University of Wisconsin, 
to whom I am indebted for advice and encouragement. 
Gonar’s silver method thus far has been a failure, likewise many 
combination stains and special fixing solutions, but it is hoped much 
may be learned by their successful application in the future. Formal- 
dehyde (8°/,) has been the most successful fixing reagent and 
HEIDENHAIN’S haematoxylin the stain most preferred. 
No comparative study has been made of the differences in the 
brain due to age and sex, although they undoubtedly exist. The 
present paper is based entirely on a study of the adult female 
brain and will be supplemented later by a study of that of the male. 
No measurements are given of the eye, optic ganglion, brain and 
the various cells which they contain because it has not been accurately 
determined what change is produced by the reagent employed. 
The optic ganglion and brain (Fig. 1) lie directly behind the eye 
in a line with its dorsal surface. The long axis of the optic ganglion 
is directed upward and backward, whereas that of the brain is directed 
upward and forward — the two being united dorsally. 
The eye is nearly spherical, though it is somewhat flattened 
posteriorly. Its greatest diameter is dorso-ventral. Posteriorly, it is 
connected with the optic ganglion in the median line by a continuous 
plate of nerve fibres extending along the upper two-thirds of the 
aspect. 
The optic ganglion is pyriform in shape with the base directed 
upward and backward. Samassa describes'it as a cube limited below 
by a hemispherical surface; this is incorrect. Along its anterior median 
line, covering nearly the entire length, it is connected, as sections 
