ITS PHYSICAL, CHEMICAL, AND STRUCTURAL CHARACTERS. 165 



Red, is very small in the blood of Man and the higher Vertebrata ; being, in 

 the state of health, not more than 1 : 50. It may undergo a great increase in 

 disease, however, as will be shown hereafter (175). In the oviparous Verte- 

 brata, the proportion is higher ; thus it has been observed by Wagner 1 to be as 

 1 : 16 in the blood of a Frog examined in February, and as 1 : 6 in similar 

 blood examined in August. In one vertebrated animal, the Amphioxus, the 

 Red corpuscles are wanting altogether, their place in the circulating blood being 

 taken by the Colorless. And in the Invertebrate series generally, the corpus- 

 cles of the circulating fluid correspond rather to the colorless corpuscles of the 

 Blood of Vertebrata, and to the corpuscles of Lymph and Chyle (which may be 

 regarded as the same bodies in an earlier stage of development), than they do 

 to the red corpuscles, which are peculiar to Vertebrata. 3 Thus, in one of its 

 most characteristic features, the Blood of Invertebrata (and of Amphioxus) 

 may be likened rather to the Lymph and Chyle of Vertebrated animals, than 

 to their Blood ; and this resemblance is strengthened by the fact, that there is 

 no distinction in the former between the absorbent and the sanguiferous vessels, 

 which, in the latter, contain the nutritious fluid in its earlier and its later stages 

 of development. Moreover, the earliest blood-corpuscles of the embryo of even 

 the highest Vertebrata are colorless ; and long after the blood has acquired its 

 characteristic hue from the development of red corpuscles, the colorless corpus- 

 cles bear a very large proportion to the red, so as even to equal them in num- 

 ber (as the author is informed by Mr. Gulliver) in the blood of foetal Deer an 

 inch and a half long, and absolutely preponderating in the blood of still smaller 

 embryos. 



.148. There can be no doubt that both the Red and the Colorless corpuscles 

 have, like other cells, a definite term of life ; and that, whilst some are under- 

 going disintegration, others are in a state of advancing development to supply 

 their places, so that the entire mass of both is undergoing continual change. 

 That a new production of Red corpuscles may take place with considerable ra- 

 pidity, we have evidence in the restoration of their normal proportion after it 

 has been lowered by hemorrhage ( 162), and in the speedy increase which may 

 be effected in their amount in blood in which they have been excessively dimin- 

 ished by disease ( 174) ; this being especially promoted by the administration 

 of Iron, and by a generous diet. On the other hand, various appearances indi- 

 cative of degeneration may be seen in the Red corpuscles ; and this especially 

 in the blood of the Oviparous Vertebrata, which usually contains corpuscles 

 almost destitute of color, and of shrunken or eroded aspect, their nuclei, however, 

 presenting a remarkable distinctness. The question now arises, in what manner 

 the two classes of Corpuscles are respectively developed, and whether they have 

 any relationship to each other. 



149. That the fully-developed Red corpuscles, when ceasing to exist as such, 

 do not give origin to new corpuscles of the same kind, may now be asserted 

 (notwithstanding the statements of former observers) to be the concurrent 

 opinion of nearly all who have in recent times specially devoted themselves to 

 this inquiry ; for although they may occasionally be seen to undergo duplicative 

 subdivision ( 104), yet this multiplication only takes place at an early period 

 of their development. The first Red corpuscles unquestionably have their 

 origin, like the original cells of the solid tissues, in the primordial cells of the 

 germinal structure ; and it is in the so-called " vascular layer" of the " blasto- 

 dermic vesicle" (CHAP, xix.), and in the mass of cells which constitutes the 



1 "Elements of Physiology," translated by Dr. Willis, p. 246. 



2 See Mr. Wharton Jones's Memoir on "the Blood-Corpuscle considered in its different 

 Phases of Development in the Animal Series," in the " Philos. Trans.," 1846 ; also " Princ. 

 of Gen. and Comp. Phys.," % 567, Am. Ed. 



