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 Ferse 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 (cceteris 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 afibrd 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. 



In 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- 



