130 DEVELOPMENT OF THE BLOOD. 



the blood from the left ventricle of the heart, from the umbilical artery 

 and vena cava superior, was composed principally of ordinary red non-nu- 

 cleated corpuscles, with a very few pale granular cells, that from the liver 

 and that also though from this source the characters of the blood were 

 less manifest from the vena cava inferior just previous to its entrance 

 into the right auricle, contained, besides red non-nucleated corpuscles, 

 a considerable number of ordinarv pale corpuscles like lymph-corpuscles, 

 and several larger pale granular corpuscles, with distinct large nuclei. 

 The appearances, indeed, presented by the blood obtained from these two 

 latter sources, but especially from the liver, were just such as would indi- 

 cate the existence of a process of rapid development of blood-corpuscles. 

 Of this process the several varieties of corpuscles found, probably repre- 

 sented so many stages from the first condition of pale spherical granular 

 nucleated cells, to the coloured, flattened, smooth, non-nucleated corpuscles.* 



With regard to the probable mode in which the liver performs this 

 office of developing blood-corpuscles, Kolliker does not offer any decided 

 opinion. He considers that it bears no particular relation to the develop- 

 ment of the proper secreting tissue of the organ, for the formation of 

 blood- corpuscles in the liver takes place even before the secretion of bile 

 commences. Professor E. H. Weber, f who also admits the importance of 

 the liver as an organ for the formation of blood in the embryo, at least of 

 birds and frogs, is of opinion that the elements of bile and the corpuscles 

 of blood stand, as it were, in a kind of complemental relation to each 

 other, the separation of the one furnishing the conditions favourable to the 

 development of the other. The seat of formation, however, both of the 

 blood corpuscles and the bile is considered by Weber to be in the net- 

 work of minute biliary ducts, and not in the blood-vessels. Certain ma- 

 terials (the contents of the yolk-sac in early embryonic life) are abstracted 

 from the latter into the former set of vessels ; and from these materials 

 are formed the elements of bile, and the corpuscles of blood : the one 

 are conveyed through the bile ducts to the gall-bladder and intestines, the 

 others make their way into the blood-vessels ; but in what manner is by 

 no means clear. 



Whatever share may be taken by the liver in the production of blood- 

 corpuscles during embryonic life, the results of the most recent observa- 

 tions on the subject of the development of the blood, especially of those 

 furnished by Kolliker, J Mr. Wharton Jones, and Fahrner,|| to the general 

 truth of which the testimony of the writer, from observations above alluded 

 to, may be added, have shewn that, in the blood of the early Mamma- 

 lian embryo, at least three several kinds of corpuscles are met with. 



* And, since the above was written, still further confirmation of the truth of such an 

 opinion has been obtained from additional examinations of the blood of other Mammalian 

 embryos at different ages. t Henle und Pfeufer's Zeitschrift, 1. c. p. 161. 



J Op. cit. Philosophical Transactions, 184 G. || Op. cit. 



