38 THE MICROSCOPE. March 
most free from germs, but, exposed to the air, they soon 
become filled with germs perfectly harmless. Under 
suitable conditions these multiply rapidly and the milk 
becomes sour, due to fermentation. - 
If the germs present give an ether or ester which hasa 
pleasant flavor, good butter results; but if they give rise 
to the formation of disagreable ethers and esters the 
butter is poor. By isolating different germs and culti- 
vating those giving a good butter, then pasteurizing the 
cream and afterward inoculating it with the good cul- 
ture, butter of the same flavor and aroma can always be 
obtained. 
The flavor of many luscious fruits and foods is dne 
either directly or indirectly to one or more of these use- 
ful plant cells. There are many ways in which the 
dreaded bacteria are of use to mankind, 
Some Figures Regarding the Blood Corpuscles. 
By T. 0. REYNOLDS, M. D. 
KINGSTON, N. H. 
There are so very many things otherwise unknowable 
which the little instrument helps us to know well, which 
would forever bein the realm of ‘‘the infinite’ were it 
not for that tiny bit of convex glass, that nothing should 
surprise us in its revelations. 
Take, for example, the red corpuscles of the human 
blood. One thirty-two hundredth of an inch is its 
diameter. One hundred and twenty one-thousandths of 
the entire blood quantity is red corpuscles. They are in- 
dividually so minute that it requires a microscope of con- 
siderable power to see them at all; and yet their number 
issuch in one man that if a chain were made of them, 
each corpuscle just touching its neighbor, it would be 
over two thousand miles long! 
Three gallons of blood in a man of 140 pounds weight 
