1907-8.] SPACE AND ITs DIMENSIONS. 321 
body were increased or decreased by the same number? It is true that 
if the earth underwent a ten-fold linear enlargement, its volume and con- 
sequently its weight, if matter filled space in the same way it does now, would 
be multiplied by one thousand. But the objects at its surface would be also 
at a ten times greater distance from the centre; consequently their 
gravity would have to be multiplied by one thousand on account of their 
own inerease in bulk, and divided by one hundred on account of their 
increased distance. That would mean gravity would be as everything 
else, ten times greater—i. e., a stone would fall through ten times greater 
space in the same time, which leaves everything as before the increase. 
Let us take the example ofa living organism. First let me ask the question: 
If the present magnitudes of the earth are preserved, could our animals 
exist if they were constructed on a much enlarged scale? Could, for 
instance, giant men twenty times as tall, giant elephants twenty times as 
high as the present ones exist? We must answer no, for when enlarging 
the linear magnitudes of the body the muscle power which is proportional 
to the square section of the muscle will increase with the square of the 
linear magnitude, but the volume and consequently the weight will increase 
with the cube. Thus the twenty times enlarged man or elephant would 
indeed be four hundred times as strong; but he would be eight thousand 
times as heavy, and consequently could not stand on his own feet. He 
would collapse into a heap. ‘That is indeed the reason why there is for 
every shape of an animal on this earth an upper limit in size above which 
bodily increase will be of no advantage, and it is also the reason why 
nature had to give up the further development of the flying birds. 
Nature has used four different principles to keep a living organism sus- 
pended in the midst of a fluid medium. 
1. The principle of surface adhesion. If the two forces of gravity 
and surface attraction act antagonistically on a body of a given shape, 
the result will be the more in favour of the surface attraction the smaller 
the body is. That is the reason why very minute particles of telluric 
or cosmic dust remain suspended in the atmosphere. Gravity is not able 
to overcome the adhesion between the surface of the particle and the 
air. This is valid not only for inorganic dust but also for organisms, and 
the moreso the smaller they are. If there are cosmic or telluric ultra- 
microscopic germs of life as Svante Arrhenius assumes, they cannot fall 
on the surface of the earth, they must remain suspended either on account 
of the adhesion between their surface and the air, or, if there is no such 
adhesion, on account of the cohesion of the particles of air, which will resist 
the passage of particles of a heavier substance if the latter are below a 
certain weight. 
