THE AMERICAN 
MONTHLY 
MICROSCOPICAL JOURNAL. 
avon. VLE. OCTOBER, 1887. No. 10. 
Elementary histological studies of the Cray-fish._VI. 
By HENRY L. OSBORN. 
CHAPTER II.—THE ‘LIVER.’—( Continued from page 169.) 
2. Gross anatomy.—When the shell of the cray-fish is removed, as diretted 
on page 167, the student will find a number of organs exposed to view. Of these 
he should find out which one is the ‘ liver’ and make it a subject of special ob- 
servation as to both its own make-up and its connections, or, as the anatomists 
say, its ‘relation’ to other organs. To make this study to the best advan- 
tage he should harden the fresh tissues somewhat with alcohol, doing it under 
close observation, to see that the different organs are not adherent to each other 
in such way as to obliterate what in the living creature are spaces between 
them. This can be quite easily accomplished if the hardening is watched under 
alens. It will take about twenty minutes’ watching to harden the specimen 
enough to make it possible to study it conveniently. 
Examination of the organ called ‘ the liver’ reveals a yellowish-brown mass 
on either side of the body, the parts on the right and left sides being separated 
from each other by the stomach and intestine and by the heart and median arte- 
ries. The two parts or halves are seen to be alike in shape, so that we can 
recognize them as a right and left half; structures thus alike, as ‘ rights’ and 
‘lefts,’ are said to be paired. Each part is seen to extend from a point near 
the front end of the stomach to the hind end of the thorax, or often into the 
abdomen a greater or less distance. Further examination shows that each 
half is divided into three lobes: an anterior lobe, which reaches forward; a 
posterior lobe, which reaches backward; and a median lobe or ‘ lateral’ * 
lobe, which lies over the anterior and posterior lobes at the break between 
them. - As the ‘liver’ is examined there can be seen a fine membrane, which, 
with teasing needles, can be removed from the surface of the lobes upon the ends 
of the fine tubes of which it is seen to be composed. This membrane is the 
sack in which the lobe is contained. It is the membrane or capsule of the 
gland. 
Still closer examination of the substance of the liver with a hand-lens will 
show that it appears to be made up of small tubes, which are blind and free 
at one end and fastened at the other, and arranged, roughly speaking, radially 
upon some attachment which is in the centre of the mass of tubes. Looking 
still more closely and very carefully we can find a sort of stem, which runs 
from the place where the three lobes of the ‘ liver’ are joined to the organ 
just behind the transparent part of the stomach and in front of the intestine 
called the ‘ pyloric portion of the stomach.’ This stem is a hollow tube 
* Huxley, The Cray-fish, p. 66. 
