[5] OYSTER CULTIVATION IN THE NETHERLANDS. 1005 
tions, but also of large oysters, cutting thick slices in different direc- 
tions; and by sketches which I have made of all these cuts, I have 
been enabled to compare these observations with those made in other 
specimens and in the usual way. In the first place, as regards the 
shape and location of the gut, or rather of the entire digestive canal, I 
found that it is not nearly as uniform as is generally supposed. I, for 
my part at least, have not seen mention made, in any work, of a differ- 
ent location of this duct. It also seems to me an important circum- 
stance that, as a general rule, the anus is located on the side and not 
at the end of the duct. A small bag is, therefore, formed at the end of 
the duct which, in one case observed by me, showed a sort of worm-like 
appendage. ‘ 
A series of sections is extremely well suited to give some idea of the 
relation between the generative organ and the liver. Whilst the gen- 
erative organ appears to thin out round the liver dorsally, it gradually 
increases in thickness towards the bottom ventral side; the liver, how- 
ever, runs, though much narrower, through to the place where the great 
cavity begins, which contains the heart and the so-called organ of Boja- 
nus. [The liver does not extend to the pericardiac space; this is the 
case in Ostrea Virginiana as well as in O. edulis, as may be shown in 
longitudinal sections.—J. A. Ryder. ] 
More than once I have had to make injections of the heart and the 
vessels originating in it, but I cannot say that these attempts have been 
particularly successful. Of larger blood vessels I could, on the large 
cuts, only distinguish one (probably the aorta). In view of the fact 
that there are still strange and conflicting opinions as to the course of 
the blood vessels, further experiments with injections cannot be too 
highly recommended. Important conclusions may possibly be drawn 
from the contraction of the heart, which continues for a long time after 
the oyster has been opened; at least various questions are thereby sug- 
gested, such as whether the motion of the so-called Bojanus organ is 
voluntary or involuntary? I think I have noticed that the diastole and 
systole did not take place simultaneously in both portions of the heart, 
but alternately. I must repeat, however, what I said above, that all 
these observations bear more or less the character of suppositions, which 
stand in need of further proof. 
As regards the method of making preparations, several of those com- 
monly in use have been tried. The hardening by means of Miiller’s 
liquid, which in the beginning seemed to promise well, cannot be recom- 
mended for fine microscopic cuts. 
It will be best to use alcohol of 70 per cent. or of 90 per cent., or pure 
alcohol, and then to embed the hardened oyster in paraffine in the well- 
known way; or also picric acid, which takes the lime out of the shell. 
In this manner small, one-year old (and younger) oysters can be pre- 
served whole. 
I need hardly say that it is very important to examine oysters of 
