96 MR. GULLIVER ON THE BLOOD-CoRPUSCLES. [Feb. 10, 
This is one of Professor Owen’s views,—a “ generalization”’ from a 
preposterous insufficiency of observations. After informing us that 
the rule is generally applicable to the placental and marsupial Mam- 
malia, he adds that, ‘the blood-disks of the marsupial species which 
derives its nourishment from the greatest variety of organized sub- 
stances, as the Perameles, which subsists on insects, worms, and the 
farinaceous and succulent vegetables, are larger than those of the 
(Spotted) carnivorous Dasyure, and those of the herbivorous Kan- 
garoo, the blood-disks of the latter, like those of the placental Ru- 
minant, being the smallest’? (Lond. Med. Gazette, Dec. 20, 1839, 
p. 475). How completely this view is at variance with the facts 
may be seen in my Tables of Measurements, of which he sometimes 
quotes the French translation by Prof. Milne-Edwards. The blood- 
disks are largest of all in the Elephant, a purely vegetable feeder, and 
in the Edentates, which do not subsist on the greatest variety of or- 
ganized substances ; while among Marsupials there are some species 
living on one kind of food, the Ursine Dasyure, e.g., that have larger 
blood-disks than those of the more omnivorous Perameles. They 
are larger in the piscivorous Seals and Otter than in the Pig, an animal 
well known to subsist on quite as great a variety of organized sub- 
stances as the Perameles ; while the blood-disks of the Pig are not 
larger than those of the Tapir, Rhinoceros, and Ass, three other 
Pachyderms and well-known vegetable feeders. And similar exam- 
ples are afforded by Birds and lower Vertebrates. 
No wonder, then, that a writer entertaining such opinions as to 
the food and blood-disks should embrace the additional error that 
their gradations of size are “ insignificant” or ‘‘ unimportant.” 
But, notwithstanding his conclusions, the truth is that this question 
of size is both significant and important. In systematic zoology we 
have already seen that the size of the corpuscles frequently affords a 
good diagnostic, both of one order from another and between genera 
or species of a single order or family; as I have more fully shown 
in the Appendix to Gerber’s ‘Anatomy,’ in the Notes to Hewson’s 
Works, in various numbers of the ‘ Philosophical Magazine’ from 
1839-42, in the second volume of the ‘Journal of Anatomy,’ and 
still further in the ‘ Proceedings’ of the Zoological Society—with 
illustrative engravings in the volume for 1862 (p. 91), and in the 
‘ Medical Times and Gazette’ from August 1862 to December 1863. 
And in a physiological point of view the size of the blood-disks is 
still more important and significant in relation to respiration and 
animal heat, as described in Lecture IX., reported in the ‘ Medical 
Times and Gazette’ for January 17, 1863, and in the abstract of an- 
other of my lectures in ‘Scientific Opinion’ for December 8, 1869. 
Indeed a field of experimental inquiry is thus opened which will 
surely yield a rich harvest when properly cultivated. What, for 
example, is the precise relation of animal heat to the proportion of 
the whole blood to the body? What is the relation of that heat to 
the proportionate quantity or aggregate bulk of the blood-disks to 
the other parts of the blood? How far is the animal heat affected, 
ceteris paribus, by the size of the bload-disks? I know of no exact 
