ON NAUTILUS AND SOME OTHER ORGANISMS. G7 
At first I sawed through the shell into one of the chambers, 
and then cut the siphuncle. This method has the disad- 
vantages of injuriously affecting the efficiency of the chambers, 
and of causing a more or less considerable loss of blood to the 
animal. The latter will, however, live in confinement about 
as long as untouched individuals. 
A young Nautilus operated upon in this way on June 26th 
was placed in the sea in shallow water, for its movements to 
be watched. It sank slowly to the bottom, and then for a long 
time made active revolving motions about the vertical axis, 
but scarcely made any progressive movements. 
On another occasion (July 10th), after several trials, I found 
that the best way of performing the operation is to saw through 
the shell in the neighbourhood of the posterior portion of the 
body of the animal, over the cardiac region, and not to tamper 
with the chambers. If the shell be held mouth downwards, 
this point lies approximately in the same vertical and trans- 
verse plane with the points where the free margin of the 
mouth of the shell merges into the umbilicus. When a large 
enough hole has been made in the shell to admit the scissors, 
the shell being still held upside down, the ventral visceral 
portion of the body usually detaches itself from the shell, or 
can be readily caused to do so, and, sinking inwards, exposes 
the root of the siphuncle, which can then be severed. On 
returning the shell to its normal position the body immediately 
resumes its normal intimate contact with the wall of the cavity 
in which it lives, and the pressure so exerted prevents any 
extensive loss of blood. Under these conditions the operation 
does not, as a rule, appear to affect the vitality of the animal 
in any degree. 
A Nautilus! which was treated in this way on July 10th, 
on being placed in the sea swam about very vigorously for 
some time in the middle stratum of water, but most of the 
time at a little distance from the bottom. On September 13th 
I operated on four more individuals taken in Talli Bay, on 
1 It should perhaps be mentioned that in this particular individual I acci- 
dentally cut into the last chamber, and plugged the opening with wax. 
