722 SPECIAL HISTOLOGY. 



Anat.," II. 2, p. 292), it is very possible that the colorless cells in ques- 

 tion, 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 develop- 

 ments, but are in a state of gradual removal. 



The view propounded by Gerlach and others, that the cells contain- 

 ing 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.* 



* [It is somewhat surprising that Professor Kolliker 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 colored corpuscle 

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

 the same blood, and of the " nucleus" of the corpuscle of the blood of oviparous Vertebrata 

 and of Jnvertebrata. 



If we consider that it is admitted on all sides: I, that the colorless corpuscle of Mamma- 

 lian blood and the lymph-corpuscle are identical. 2, that these are identical with the color- 

 less and lymph-corpuscles of other Vertebrata. 3, that in the latter, the colored blood-corpuscle 

 proceeds from the colorless corpuscle : only three hypotheses can well remain with regard 

 to the relation of the blood- and colorless 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 be in 

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

 animals, the blood-corpuscle is found in three successive phases of development : that of 

 a cell with granular contents the granules being either fine or coarse ; that of a cell with- 

 out any contents except the " nucleus'' the cell being either colorless or colored ; and, 

 finally, in that of a free celloeform " nucleus," which is either colorless or colored. We 

 have thus three phases, each of which has two stages. The phases of granule-cell and nu- 

 cleated-cell are met with in all Vertebrata ; Amphioxus alone going no further than the 

 colorless stage of the second phase. In the oviparous Vertebrata the blood-corpuscle pre- 

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

 all their stages ; but two of the latter, that of the colored nucleated cell and that of the 

 colorless free cellseform nucleus, occur but rarely and* scantily. That the red corpuscle of 

 Mammals is the cella?form " nucleus" of the nucleated-cell stage, set free by the bursting of 

 this cell itself, and become filled and red by the secretion of globulin and coloring matter 

 into its interior, is strongly evidenced by the correspondence in size between the " nucleus" 

 and the red corpuscle, as the latter varies in different animals. In the Elephant the red 

 corpuscle is very large, and in the Goat it is very small; the "nucleus" of the colorless cor- 

 puscle varies correspondingly. There is a similar correspondence in form ; and it is remark- 

 able that in the Paco, whose red corpuscles are, when fully formed, elliptical, while the 

 nuclei of the colorless corpuscles are for the most part circular, younger less-colored red 

 corpuscles are met with, which are circular and correspond in all respects with the " nuclei" 

 of the colorless corpuscles. In dealing with objections which might be raised from the 

 chemical and physical differences between the red corpuscles and the " nuclei," Wharton 

 Jones shows that these almost disappear if we select the youngest state of the red corpuscle 

 as one term of the comparison. 



It is rare to meet with the transition stage between the phase of nucleated cell and that 

 of " free cellseform nucleus" in the blood of Man. We have, however, recently recorded 

 an observation of the kind in unaltered blood (" Quarterly Journal of Micr. Science," vol. i. 

 p. 145), where a well-marked red corpuscle was observed within what would otherwise 

 have been regarded as a colorless corpuscle, and occupying the place of its " nucleus;" and 



