1862.] OF THE BLOOD OF VERTEBRATES. 95 
Society, October 14, 1845, and in subsequent numbers; in the Ap- 
pendix to the English version of Gerber’s ‘Anatomy ;’ and in my 
‘Notes to the Edition of Hewson’s Works,’ printed for the Sydenham 
Society. The exceptions among the Fere were long since especially 
noticed by me; and exceptions among aberrant species of any family 
may be generally expected. But no example has hitherto been dis- 
covered (ceteris paribus) of any one natural family, subject to the 
exceptions implied, in which the largest corpuscles do not prevail 
among the large species, and the smallest corpuscles among the small 
species of that family. And this is the way in which I have put or 
intended the rule as to the relation between the size of the corpuscles 
and that of the species in the higher Vertebrata. But I never ex- 
tended it to the two lowest classes, as may be seen from my measure- 
ments of their corpuscles, and in the papers just cited. On the 
contrary, some of the great Ophidia, as Python, are there shown to 
have smaller corpuscles than such little species as Coluber and Anguis. 
And this seems to be sufficient notice of the so-called exceptions of 
certain reptiles and fishes erroneously adduced, in a former Part of 
the ‘ Proceedings’ of this Society, against my observations. 
As to the comparative smallness and abundance of the corpuscles 
of the Tunny, if, as there is reason to suppose, this be a warm-blooded 
fish, the fact would be interesting as a probable indication of a special 
adaptation. Dr. Davy, the highest authority on this question, has 
long since proved experimentally that its ally (the Bonito) has warm 
blood, and that the blood of the Tunny is so very rich in red cor- 
puscles as to afford a remarkable contrast in this respect to some of 
the cold fishes with which he made the comparisons. I long since per- 
ceived that there must be some sort of connexion between the size of 
the red corpuscles and the respiratory function ; and Dr. Davy in 1844 
held, as the result of precise observations, that these corpuscles are 
important in relation to animal heat. They have long been consi- 
dered as carriers of oxygen. More recently, Professor Milne-Edwards, 
in his excellent ‘Legons sur la Physiologie,’ has made this subject 
his own as far as concerns the tendency of the red corpuscles to be 
of smaller size in proportion to the general activity and respiratory 
demands of the animal, and vice versd. His observations are numerous 
and interesting on this point ; and the many exceptions as to regular 
gradation of size, such as may be seen in the present woodcut, and, 
further, in the ‘Tables of Measurements’ already referred to, are 
fairly recognized by him. But our knowledge is not at present suf- 
ficiently advanced to admit of a calculation of the disturbing cir- 
cumstances, of which hybernation and peculiarities of structure and 
habits, and differences in the relative proportion of the red corpuscles 
to the other proximate constituents of the blood, may be among the 
number. 
Tn Mammalia and Birds I have long since observed some tendency 
to a relation of size between the red corpuscles and pulmonary air- 
cells and capillary vessels. And when the beautiful observations of 
the late Professor Quekett showed the value and import of the bone- 
cells, it was immediately seen that there is a like disposition to a re- 
