271 
the effects, that they were afraid of being poisoned in removing the 
blubber, and would not persevere in using the harpoons.* 
The paper concluded with observations, showing that increased 
facilities might be secured, in consequence of the comparative ease 
with which concentrated prussic acid might now be made and pre- 
served in hermetically sealed tubes, and likewise because poisons 
were now known even more potent than hydrocyanic acid, 
2. Notice regarding the Branchial Sac of the Simple xiscidise. 
By Andrew Murray. 
In a paper which I read last year before this Society, “ On the 
Structure and Functions of the Branchial Sac of the Simple Asei- 
dice,” I stated that I had fed and injected ascidise with indigo and 
other coloured sea-water, and that in those so fed, the coloured 
material was never found on the exterior of the sac, but always 
deposited on the inner wall, and that injection by the mouth into 
the sac failed to push the coloured matter through its walls, except 
by rupturing them. 
These experiments were not isolated or few in number. I showed 
the results to various friends — among others, Professor Goodsir, Dr 
Wright, and Dr Cleland — and never, in any of the experiments which 
I made, did a single instance occur of the indigo passing through the 
stigmata of the sac ; and, in that paper, I naturally reasoned from 
this fact. Subsequent observation has shown me that, in relying 
upon these negative instances, I was generalising too hastily. Since 
I read that paper, I have in two instances found, on feeding the 
Ascidia virginea with indigo, that it had passed through the windows 
of the sac and was partially deposited on each side of the sac, and 
some of it sticking in the meshes ; and I hasten to correct the erro- 
neous impression conveyed by the negative instances in my former 
paper. Of course, ail the reasoning in it, founded on the supposed 
impenetrability of the sac, falls to the ground ; and it would appear 
that my error has arisen from the animal having the power of re- 
jecting or passing through these stigmata the contents of the sac as 
it pleases, which accounts for various other observers having seen 
* Since the Author’s paper was read, he has received distinct information, 
that at the first trial, the whale “ sounded,” but in a surprisingly short time 
came up again — dead. 
