THE AMERICAN 
MONTHLY 
MICROSCOPICAL JOURNAL. 
Vou. VIII. NOVEMBER, 1887. No. 11. 
Elementary histological studies of the Cray-fish.—VIL. 
By HENRY L. OSBORN. 
CHAPTER II.—( Continued from page 185.) 
4. Histology.—We have now considered the anatomy of the liver of the 
cray-fish and find it composed of these different parts, viz: the capsule or 
investing sack of the gland; the lining of the passages of the gland, or the 
glandular epithelium; and the blood contained in the blood-space. The 
structure—that is, the shape and size—of the cells composing these, together 
with any facts we can learn as to the parts composing these cells, if any can 
be found, form the subject-matter of histology. To prosecute this study it 
is positively necessary that the student be furnished properly prepared sec- 
tions. The study of minute anatomy can be prosecuted with no great detri- 
ment upon sections which are not preserved in the most perfect manner, or 
cut with the extremest skill. A large share of the study, which is most com- 
monly called histological, is more exactly of minute anatomy, the particular 
study of the cell itself not being its object so much as the study of the arrange- 
ment of the tissue of which it forms a part. But when the details of struc- 
ture of so small and delicate a body as an ultimate cell of any tissue is to be 
investigated, great caution must be observed to assure one’s self that it has 
not been given some unnatural look under our treatment. And this is a 
matter of great difficulty, and gives rise to most of the discussion as to the 
relative merits of different modes of treatment of sections. In estimating the 
value of a method, then, we try to see in how far it fulfils these requirements ; 
that the cell shall not be distorted by sudden osmotic changes; by sudden 
great changes of temperature; by handling which would tear its delicate 
walls, or subject to the action of agents which would remove any of its parts. 
We cannot, at this time, go into details upon this portion of the subject, for 
space does not permit. We can only suggest this hint of the principle on 
which the choice of histological methods is based. Let us then make an ac- 
tual study of the cells of the various sorts which make up the organ called 
the liver. 
1. The glandular epithelium.—Where cells cover in a space, forming 
a wall for that space, they are usually called, collectively, ‘an epithelium ;’ 
and one individual cell is called ‘ an epithelial cell.’ To learn the cellular 
structure of the glandular epithelium requires the use of somewhat high mag- 
nifying powers and well prepared sections. The section shown at figure 1 
in the plate (ix, p. 183) is sufficiently thin to show the cellular structure of 
the epithelium, but it is not magnified enough to do so. An experienced 
observer would be able from this section, which shows more than the figure, 
to arrive at a correct inference as to the shapes of the cells of the epithelium, 
