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Show 1875.J RED BLOOD-CORPUSCLES. 475 the significance is intimated of the comparative minuteness of the corpuscles in the small species of single natural orders or families of Apyrenoemata and throughout the class of Birds. Since the publication, upwards of a quarter of a century ago, of m y Tables of Measurements, I have made so many additions and revisions by new observations, several of which have never been published, that nothing short of the present paper will suffice to give such a fair view of the whole series of averages as will be most useful for future reference, in relation to questions, often arising and likely to increase, concerning the import, whether taxonomic or physiological, of the sizes of the red corpuscles of the blood. The original Tables, which appeared in the ' Proceedings' of this Society (P. Z. S. 1845, p. 93) and in the Sydenham Society's edition of Ilewson's Works, 8vo, 1846, followed m y extensive observations on the same subject in the 'Lond. and Edin. Phil. Mag.' January 1840 to August 1842, and in the Appendix to the English version of Gerber's Anatomy, 8vo, Lond. 1842. Those measurements have been added to piecemeal up to the present year; and the tables from Hewson's Works were converted into French millimetres and transferred by Milne-Edwards to the first volume (8vo, Paris, 1857, pp. 84-90) of his great work already cited. Of course, as linear measurements only are used, all my remarks as to the sizes of the corpuscles are to be understood accordingly. The measurements now recorded show the results of the labours of many years, and are far more copious than any others known to me, and, with the observations connected therewith originally, proved sundry facts, such as, e.g.: - the singular minuteness in the Tragulidse of the red blood-corpuscles, their largeness in the Edentata and pinniped Ferse, and batrachian character in Lepidosiren; the comparative sizes of the corpuscles in several of the subsections of the vertebrate subkingdom ; the relation of those sizes to the sizes of the species in the orders or families of Apyrensemata and throughout the class of Birds ; the essential difference between the Pyrensemata and Apyreneemata, with the conformity of the Lampreys to the former and of the Camels to the latter type, and the identity of the corpuscles in placental and implacental Mammalia. On some points the engraved page in the ' Proceedings of the Zoological Society,' Feb.25,1862, contains such errors of omission and commission, caused bv strange accidents, and is so deficient in later observations, that it is now given with the needful corrections and additions in illustration of the present paper. Specimens of the corpuscles in the different classes and orders are all drawn side by side to a uniform scale, of which each one of its ten divisions stands for J<JVO~ °f a n English inch, and the whole length of the scale for T ^ of an inch. The same design will be adopted, with unimportant modifications in the arrangement of the corpuscles and divisions of the scale, in the next edition of Professor Beale's excellent work on the microscope. Historical notices of the observations of m y predecessors and contemporaries are given in the memoirs cited above, and in the notes to the edition of Hewson's Works already mentioned. |
