73 
and those of certain other Mammals. 
ten divisions, and one as large as eighteen divisions ; large and 
small forms were not searched for, however. The size most 
frequently measured was fifteen divisions, or * 00030 of an inch. 
Measurements of the Red Corpuscles of the Dog, from Five Individuals. 
Mean Diameter. 
Number of 
Corpuscles 
Decimal of 
Decimal of 
an English Inch. 
a Millimeter. 
1. Mongrel terrier, dry 
50 
•000292 
•00740 
2. Same animal do 
54 
•000299 
•00759 
3. Anot lieu-mongrel terrier, dry (H) 
50 
•000290 
•00737 
4. Same animal, moist (H) .. 
50 
•00028S 
•00731 
5. Scotch terrier do. (H) .. 
50 
•000291 
•00739 
6. Same animal do. (H) . . 
50 
•000289 
•00734 
7. Do. do. (H) .. 
49 
•000287 
•00729 
8. Spitz dog, dry (H) .. 
52 
•000285 
•00724 
9. Black-and-tan, moist (H) 
50 
•000290 
•00737 
In each of these measurements- of dogs’ blood, precisely as in the 
case of those of human blood, the great majority of the corpuscles 
measured from twelve to seventeen divisions of the eye-piece micro- 
meter ( , 00024 to *00034 of an inch) ; out of the whole number 
measured, four were as small as ten divisions, but nine larger than 
seventeen were encountered. As with the human blood, however, 
large and small forms were not searched for, but all the perfectly 
formed corpuscles brought into view by the movement of the stage, 
were measured as they passed under the micrometer without selec- 
tion, until the required number was recorded. The size most 
frequently measured was fifteen divisions, or -00030 of an inch, 
precisely as in the case of human blood. 
It will be observed that three of the above means for human 
blood, Nos. 1, 3, and 7, are a trifle larger than any of those of 
dogs’ blood ; and two of the latter, Nos. 7 and 8, are a trifle smaller 
than any of those for human blood. All the other means for the 
dog are within the range of the values found for human blood, and 
the majority of them are each identical, even to the last decimal 
place, with some one of those found for man. 
I may, moreover, remind the reader in this place, that the varia- 
tions between the mean diameter assigned to human blood by 
different observers are quite as great as the variations recorded by 
any of them between the blood of man and the dog, or even 
greater. Passing by the older measurements, some of which, as a 
matter of curiosity, I have given in a foot-note,* I may cite, besides 
* A list of the more important of these older measurements will be found in 
the Mensiones Micrometricae of R. Wagner (‘Partium Elementarium Organorum 
quae sunt in Homine atque Animalibus Mensiones Micrometricae,’ Erlangen, 1834). 
Most of these are included in the more complete list given by Louis Mandl 
