32 Vital Functions of the {y.^^^lJ^'i:^' 
magnifying power of the two bodies. At the meeting above re- 
ferred to, Mr. Heisch criticized the form of the central prism. I 
have abandoned that indicated by Mr. Heiscb, because the vertical 
surface of the rectangular prism being parallel to the central pencil, 
a certain part of the light is reflected by this surface, and produces 
a kind of fog over the image. I have convinced myself of the 
perfect harmlessness of a parallel plate of glass placed in the direc- 
tion of the image. In conclusion, Mr. Heisch mentioned the fact 
that many persons had used the new form with more ease than the 
remarkable arrangement of Mr. Wenham. The cause is to be 
fou jd in this physiological fact ; — that there is a certain difficulty 
in combining the strongly convergent images of the Wenham 
binocular, and also, as a second source of uneasiness, that an ap- 
parent diminution of the size of the image results from the great 
convergence of the pencils. It is therefore to be desired that all 
binocular arrangements should be less convergent. 
YI.— 0^ the Vital Functions of the Deejp-sea Protozoa, 
By G. C. Wallich, M.D., F.L.S. 
The confirmation which my views regarding the presence of animal 
life, and the existence of an abundantly distributed fauna at vast 
depths in the ocean, have received, through the recent researches 
of Dr. Carpenter and Professor Wyville Thompson, affords a 
fitting opportunity for reviewing the state of - our knowledge of 
such vital phenomena as are involved in the nutrition of the 
abyssal Protozoa, and of determining how far such phenomena are 
reconcileable with preconceived notions which prevail regarding 
the conditions under which alone their existence can be sustained. 
In order to place the question in an intelligible light, it is neces- 
sary to call attention to the assumed law which presupposes that 
animal existence cannot be sustained without the previous manifes- 
tation of vegetable life ; and to point out why this law cannot be 
regarded as valid in the case of organisms inhabiting the depths of 
the ocean. 
It has been very generally laid down by physiologists, as indi- 
cating the line of demarcation between the lower portions of the 
animal and vegetable kingdoms, that, whereas the animal receives, 
into a cavity within its body, organic compounds already formed 
which it converts into nutriment, the vegetable lives upon inorganic 
elements which it imbibes through its external surfaces only. 
And, doubtless, this definition holds good as regards those Protozoa 
in which the difierentiation of the sarcode has arrived at a certain 
limit. It shall be my endeavour, however, to show that in the case 
