95 JOURNAL AND PROCEEDINGS. 
while. | Now let me briefly set out the requirements of higher 
animal life as we know it, sufficient air, moisture, a suitable 
temperature, light and food. If the first four be provided, the 
last is practically assured, as vegetable life would, under such 
conditions, certainly exist also to provide it. On earth man, 
for example, requires on the average a lung capacity of 20 
cubic inches of air to supply the necessary oxygen to sustain 
life. He finds his lung capacity ample under ordinary circum- 
stances, but let him ascend about 16,000 feet above sea level 
and he will find that it is very difficult for him to get enough 
air into his lungs to keep him comfortably warm; and putting 
on clothes is a good deal like trying to keep up the heat of a 
stove by shutting off the drafts and covering the metal with an 
asbestos jacket. 
Now, according to Prof. G. C. Comstock, of the observa- 
tory of the University of Wisconsin, the Moon’s atmosphere is 
at most only one ten thousandth part of that of the earth, so 
that on the moon a man would require, supposing the composi- 
tion of the air there to be the same as here, a lung capacity for 
200,000 ctibic inches (20 cubic inches x 10,000), or if we sup- 
pose the Moon’s atmosphere to be all oxygen, instead of about 
one-fifth oxygen, as on earth, a lung capacity for 40,000 cubic 
inches (23 cubic feet) would suffice. Fancy a 6-foot man 
needing a chest from 2,000 to 10,000 times greater in capacity 
than he now owns in order to pick up enough oxygen to keep 
the blood red in the remainder of his somewhat overshadowed 
body. Even for cold blooded animals such an atmosphere 
would not suffice, and, supposing that by some change in 
structure an animal could exist in such an atmosphere, the 
second condition, moisture, would be unattainable. Proto- 
plasm, the ultimate constituent of all living organisms, contains 
80 per cent. to 85 per cent. of watef and 15 per cent. to 20 per 
cent. of solids, and this water is necessary for the maintenance 
of the metabolic processes constituting its life. Now water, at 
ordinary atmospheric pressure of about 30 inches, or 760 MM. 
mercury can exist in either the solid, liquid or gaseous conditions. 
It, however, we reduce the pressure below 4.6 MM of mercury 
