82 THE AMERICAN MONTHLY [May, 
the cray-fish in a pint of water, to which five cc. of chloroform or ether have» 
been added; in a few minutes he will die. Removing him from the fluid,* 
cut off the anterior part of the carapace, and, carefully lifting the fore-end of 
the stomach, cut around the shell on the ventral side close in front of the man- 
dibles, and remove the whole front end of the cephalothorax. The two green 
glands can now be seen lying next to the shell on the ventral side; they are 
of a brownish color, and the whitish sack lying over them will be conspicu- 
ous. Place these in strong alcohol (95%) for several hours, and they will be 
changed from soft bodies, which tear too readily to permit dissection, to tough 
and firmer ones, and can be dissected in a watch-glass, under alcohol, 
with a simple dissecting microscope, and the gross structure demonstrated 
clearly. Examination will show that the apparatus of one side is entirely 
independent of the other, and that each is composed of two parts :—First, a 
very thin-walled and delicate sack which lies above, the second, a compact 
body of a very flattened spheroidal shape, the glandular portion. 
I. Zhe sack may be seen to be hollow; in fact, unless very great caution 
has been observed, the roof of the sack will bave been broken into, displaying 
its cavity. The cavity of the sack may be followed forward, the sack nar- 
rowing into a tube, which runs over the front of the more solid part of the 
apparatus, and beneath it, to open by a hole through the shelly basal joint of 
the antenna. The portion of the sack which is applied to the upper surface 
of the glandular portion of the apparatus will be found loosely adherent, ex- 
cept at one place where it appears to run into the substance of the glandular 
portion, and in several places where narrow threads may be seen to run 
across from it to the glandular part. 
Il. The glandular portion is flat or slightly concave above, where it lies 
against the sack, and convex below, where it lies against the shell of the ven- 
tral side of the head region of the body. Close examination of this under 
simple microscope (15 diameters) will show what appears to be a compact 
body coarsely granular. If, with a scalpel, a few slices are cut across it, it 
will be seen to be of a spongy texture, partitions running through it in all 
directions and cutting it up into irregular cavities. It will be seen that there 
is no trace of an opening to the gland upon its under surface, but close exam- 
ination of the upper surface will show that the hollow of the sack communi- 
cates with the interior of the glandular portion.f 
2. Preparation of the sections.—There are many modes of treatment 
to produce the same final result in cutting the sections. In all these the pur- 
pose is to preserve the cells in the most natural manner, to harden them so 
that the thinnest sections can be cut, to stain so as to make most easily seen 
the naturally very transparent protoplasmic parts, to mount the section so as 
to preserve the natural relations of all the parts, and, finally, to permanently 
protect the section in a medium which will prevent any change after the 
mounting has been completed. A full discussion of all the various processes 
for accomplishing all these purposes would be very interesting; but not suffi- 
ciently elementary for the purpose in hand. I intend rather to give an exact 
account of the actual processes employed in the preparation of the sections 
to be afterwards described, with such remarks upon them as will, I trust, 
enable any one to put a similar structure through a similar course of treat- 
ment and arrive at as satisfactory results. The following is a copy from my 
laboratory notes upon the history of the sections from which plate IV was 
drawn :— 
* The chloroform or ether will not mix with the water, and may be collected and saved for a future occasion. 
+ A good figure to illustrate the general relation of the parts of the green gland to each other and to the rest 
of the body is shown in Huxley’s The Cray-fish, p. 83, fig. 18. 
