iit MICROSCOPE. 
Vou. VI. ANN ARBOR, MAY, 1886. No. 5. 
ORIGINAL COMMUNICATIONS. 
BLOOD MEASUREMENTS. 
A. WATERHOUSE, M. D., JAMESTOWN, N. Y. 
HERE has been considerable controversy within the past few 
years, in regard to the possibility of distinguishing the 
blood corpuscles of man from those of some of the lower ani- 
mals, and assertions have been made that might mislead those 
who have had no opportunity to'‘make investigations for them- 
selves. 
Having made many measurements of blood corpuscles of 
different animals for several years past, and well knowing that 
itis more popular to be positive, though in error, than to be 
sceptical, even where facts will not warrant a positive opinion, 
I am induced to give you some of my own measurements made 
during the past ten years. 
They have been made under very favorable circumstances, 
and with great care. I have made many measurements of blood 
corpuscles in their own serum, in various media, and in other 
ways, but have yet to find any way in which they change less’ 
in size than that of drying quickly upon a clean glass surface, 
and in preparing my specimens I have used the fresh blood 
spread upon a thin glass cover so thinly that the corpuscles 
should not touch each other and become disturbed, and gently 
warmed so that the blood may dry quickly. 
A ring was made with cement upon a slide and the cover 
inverted upon it, so that the blood is on under side of the cover. 
The ring serves to prevent the blood from touching the slide 
and forms a closed cell excluding all extraneous matter and in 
this manner will keep for years. 
The measurements were made with a fine 1-16 inch objec- 
tive, and D eye-piece micrometer, giving a magnifying power 
of about 2,800 diameters. The value of each division of my 
