98 Tue Microscope. 
eye-piece micrometer was carefully ascertained by a stage mi- 
crometer, ruled by Prof. W. A. Rogers to 1-2,500 of an inch, and 
found to be of the value of .000,035,55-+’ or 1-28,125 inches, and 
I could estimate to one half of one division. The relative length 
of tube, from eye-piece to objective, was maintained the same, 
and the collar adjustment was placed at the same point of cor- 
rection. 
I have arranged the measurements in the order of size of 
corpuscles rather than that of species of animals, as being more 
easily found and compared in the table. 
In comparing these measurements with the wonderful 
tables of Dr. Gulliver it must be remembered that he took the 
average of only ten measurements under a magnifying power 
of only 500 or 600 diameters, and that they were made between 
1839 and 1846, when he could not have had as good glasses as 
are now made, and further that his standard of measure might 
not have been as accurate as those with which Prof. Rogers is 
now able to furnish us. 
I wish the reader would compare these tables with the meas- 
urements of the late Dr. J. J. Woodward in his plates of Blood 
Corpuscles of Man, Dog, and Guinea Pig, although if the col- 
umns of figures in my original measurements be divided into 
tens or even twenties the variations oftentimes would be greater. 
MEASUREMENTS OF BLOOD CORPUSCLES OF MAMMALS. 
Max. .000,497+' or 1-2,009 in. 
Foetus of Grey Gopher. 100 meas. { Min, .000,855+' or 1-2,812 in. 
Aver. .000,429+' or 1-2,328 in. 
Max. .000,426,6’ or 1-2,344 in. 
Indian Elephant. 200 meas. | Min. .000,302,2’ or 1-3,309 in. 
Aver. .000,399' or 1-2,778 in. 
Max. .000,391’ or 1-2,557 in, 
Foetus of Cat (Felis Dom.) 200 meas. | aie .000, 284’ or 1-3,516 in. 
Aver. .000,333' or I-2,996 in. 
Max. .000,355,5+' or 1-2,812 in. 
Man. 200 meas. | Min. .000,266,7' or 1-3,750in. 
Aver. .000,328,3' or 1-2,996 in. 
Gray Rabbit Max. .000,355+' or 1-2,812 in. 
: (Lepus Sylvestris). 200 meas.; Min. .000,284+' or 1-3,516 in. 
Aver. .000,326+' or 1-3,054 in. 
‘Woodchuck, Max. .000,391' or 1-2,557 in. 
(Arctomy Monax) 200 meas.{ Min. .000,284' or 1-3,516 in. 
Aver. .000,326' or 1-3,071 in. 
Max. .000,355’ or 1-2.812 in. 
Man 200 meas. | Min. .000,267’ or 1-3,705 in. 
Aver. .000,328’ or 1-3,089 in. 
