4 : ; NATURE AND LIFE. 
serve how the amazing revelations of the microscopic world 
have justified his eloquence and foresight ; and yet this mi- 
croscopic world, whose minutest representatives, such as 
vibrios and bacteria, are hardly less than the ten-thousandth 
part of #4, of an inch, how coarse it is compared with the 
particles thrown off by odorous bodies, and with the incon- 
ceivably minute quantities which chemistry, physics, and 
mechanics, now measure without seeing them, or make 
their existence plain without grasping them. We may 
mention some instances which can give us an idea of these. 
According to Tyndall, when very minute solid particles, 
smaller than the luminous waves, are diffused in a medi- 
um traversed by light, the light is decomposed in such a 
way that the least waves, the blue ones, predominate in 
the reflected rays, and the largest ones, the red waves, in 
the transmitted rays. This ingenious physicist thus ex- 
plains how the blue color of the sky depends and must de- 
pend on the existence of solid particles, excessively minute, 
diffused in infinite quantity through the atmosphere. Tyn- 
dall is not disinclined to the idea that these imperceptible 
atoms might very well be no other than those germs of 
microscopic organisms the presence of which in the atmos- 
phere has been proved by the labors of Pasteur, as well as 
the part they take in the phenomena of putrefaction and fer- 
mentation. The ova of these beings, which are barely vis- 
ible under the microscope after attaining full development, 
and of which the number, ascertained by the most decisive 
evidence, confounds the boldest imagination, these would be 
the elements of that vital ether, as we have termed it, that 
dust which gives its lovely blue tint to the vault of the sky. 
“‘ There exist in the atmosphere,” Tyndall says in closing, 
“particles of matter that elude the microscope and the scales, 
which do not disturb its clearness, and yet are present in 
it in so imnrense a multitude that the Hebrew hyperbole 
of the number of grains of sand on the sea-shore becomes 
