THE BLOOD AND THE LYMPH. 347 



appears to me, that this question must be approached with very 

 great care, so long as the transition of the colourless cells into 

 blood- corpuscles has not been directly observed, which in this 

 case has by no means been done. At present we are far too 

 little acquainted with the vital relations of the colourless cells 

 in the blood to conclude, merely from their existence, upon a 

 formation of red blood-cells, and especially when we remember 

 the facts stated; since, as I have elsewhere shown (Mikros. 

 Anat., II, 2, p. 292), it is very possible that the colourless cells 

 in question, in the splenic and hepatic veins, are derived from 

 the parenchyma of the spleen, are only accidental constituents 

 of the blood, and as their frequently multiple nuclei seem 

 to indicate, undergo no further developments, but are in a state 

 of gradual removal. 



The view propounded by Gerlach and others, that the cells 

 containing blood-corpuscles, which are met with frequently in 

 the spleen and occasionally in the blood, have a relation to the 

 formation of blood-cells, must decidedly be rejected, since the 

 blood-corpuscles of all these cells are in a state of dissolution. 1 



1 [It is somewhat surprising that Professor Kblliker should not have thought it 

 necessary to consider the doctrine advocated by Wharton Jones (1. c), the truth of 

 which the latter writer may, we think, be almost said to have demonstrated, viz. that 

 the coloured corpuscle of the blood of Mammalia is the homologue of the " nucleus" 

 of the colourless corpuscle of the same blood, and of the " nucleus" of the corpuscle 

 of the blood of oviparous Vertebrata and of Invertebrata. 



If we consider that it is admitted on all sides : 1. that the colourless corpuscle of 

 Mammalian blood and the lymph-corpuscle are identical. 2. that these are identical 

 with the colourless and lymph-corpuscles of other Vertebrata. 3. that in the latter, 

 the coloured blood-corpuscle proceeds from the colourless corpuscle : — only three 

 hypotheses can well remain with regard to the relation of the blood- and colourless 

 corpuscles of Mammalia — viz.: that in the text ; that which supposes that they have 

 an independent origin ; and that advocated by Wharton Jones. The two former 

 of these hypotheses are deficient in all positive basis, and the first appears to us 

 extremely improbable. On the other hand, the third theory appears to he in 

 harmony with all the known facts, and opposed to none. It is, shortly, that in 

 Vertebrate animals, the blood-corpuscle is found in three successive phases of de- 

 velopment : that of a cell with granular contents — the granules being either fine or 

 coarse ; that of a cell without any contents except the " nucleus" — the cell being 

 either colourless or coloured ; and, finally, in that of a free cellae-form " nucleus," 

 which is either colourless or coloured. We have thus three phases, each of which 

 has two stages. The phases of granule-cell and nucleated cell are met with in all 

 Vertebrata; Amphioxus alone going no further than the colourless stage of the 

 second phase. In the oviparous Vertebrata the blood- corpuscle presents the two 

 first phases in both their stages. In the Mammalian cell, the phases exist in all their 



