THE AMERICAN 
MONTHLY 
MICROSCOPICAL JOURNAL. 
Wor VIII. JULY, 1887. No.7. 
Elementary histological studies of the Cray-fish—II1. 
BY ENRYe- LE O'S BO RINE 
(Continued from page 105.) 
4. Interpretation of the sections.—The problem for the histologist is 
to determine the natural size and shape of every kind of cell in the subject of 
his study and the way they are all put together, and, further, to determine, 
if possible, the internal structure of the cell, its parts, their constitution and 
arrangement. He has not reached the end of his study until he has answered 
all questions relative to the construction of this minute body only ;,1,, of an 
inch across. The difficulties which beset him arise from four general sources, 
viz :—Uncertainty as to the perfect operation of his preservative methods ; the 
fact that his view is of a surface, not of a solid body, so that he can look at the 
cell from only one single standpoint ; the fact that the cells are so delicately 
walled that their outlines are often invisible, and usually almost so; and the 
constant possibility of meeting diseased cells, cells in which pathological 
changes have taken place, or places where some abnormal or irregular oc- 
currence has been hit upon. In the solution of his problem he must keep 
all these drawbacks in mind; test his observation by them before he reaches 
a conclusion. 
Let us now set before ourselves the task of determining the facts regarding 
the cells of the walls of the alveoli. In attempting this I would urge upon the 
student the need of recognizing the vast gap between what he sees and what 
he may assure himself to be the case by inference. In the order of study, what 
one sees comes first, but to what one has seen in any one place is to be added 
what he sees in every other place, and from these observations a completed 
notion must be derived. Unless he sees the necessity of thus looking from 
point to point in his section to form a composite photograph, so to speak, he 
will never get beyond the most primary part of his study. Most students are 
at the outset met by this difficulty. They pursue the study of the section with 
deepest interest, but they fail entirely to transfer their study from the section 
to the organ to which it belongs, and to interpret from the sections the struc- 
ture of the organ. Such a course robs the study of its proper fruit, and the 
harder work is all done, and the worker leaves his task before he has reaped 
its legitimate reward. 
I shall not attempt here to show what reasons there are for accepting the 
appearances of the cells as natural. If the cell has such a delicate wall the 
natural supposition would be that, treating it with absolute alcohol and chlo- 
roform and hot paraffine would distort the frail structures into unnatural shapes. 
The reasons for believing, in any case, that it is not injured are numerous, 
but, as they depend upon considerable prior information, they cannot with 
value be discussed at present, and the observer must accept at the start the 
