60 PROF. LIONEL S. BEALE, F.R.C.P., F.R.S., ON VITALITY. 
Society, and to the Victoria Institute, and several works— 
Protoplasm, Bioplasm, Vitality, ete. 
Biological investigation has been indirectly greatly 
advanced by bacteriology. Very high powers, of good 
definition, magnitying 600 times or more, are required in both 
departments. We have been able to discern living particles 
which are less than ;,1,,;th of an inch in diameter, and 
many important facts relating to “life” have been made out. 
Bacteria in their millions might le in a space less than a 
quarter of an inch square without being crowded. Many of 
these minute organisms are unpleasant creatures, and some 
are dangerous, but the great majority of thei are perfectly 
harmless. Millions and millions of harmless bacteria exist 
outside and inside most living things, multitudes are present 
in the food we eat. In every cell of vegetables which are 
kept by the greengrocer for twenty-four Thome. or even less, 
they abound; so that there is nothing to be feared except m 
regard of certain specific kinds. 
Tam old enough to recollect the time when because one 
talked of things being magnified 700 or 800 diameters we 
were looked upon as very fanciful creatures, speaking 
familiarly about strange and unheard-of things. But now 
microscopic powers may be used, and with success, which 
magnify more than 1,500 diameters. Let us consider what 
this enlargement means. By “one thousand linear” or 
“one thousand diameters” we mean that a little particle, 
whatever may be its nature, is made to appear a thousand 
times longer or wider than it is, and the use of the word 
linear 18 important. We measure merely in one direction, 
either from right to left or from above downwards over the 
field in one direction only. 
A thousand diameters in these days is not very much; but 
if a thing were enlarged only 300 or 400 diameters you 
would er surprised Ao large it would appear. If the body, 
say, of a frog, could be magnified in this degree. 200 or 300 
diameters, it would appear to be 60 or 70 feet long. So, a 
man magnified in the same degree as a particle of one of his 
tissues might be under the microscope, would appear to 
be as tall as a high mountain. 
The relative proportion of bioplasm or living matter in a 
tissue is much larger in young than in fully formed animals 
of the same kind, and in old age the proportion becomes less 
and less. The proportion of living matter in the growing 
embryo is considerable, and the very young embryo consists 
