( 16S ) 



Against tliis view Sciiafer, Sedgwick-Minot and Ran vier (vvliose 

 experimental proof has however a year ago been disposed of by 

 Vosmaer) protested. The two first-named lock upon the non-nucleated 

 mammalian blood-corpuscles as plastids, that are formed in cells in 

 an analogous way as are the chlorophyll-granules in vegetable 

 cells. The majority of the remaining investigators consider the non- 

 nucleated mammalian blood-corpuscles as cells from which the 

 nucleus has either been extruded (Rindfleisch, van der Stricht, 

 BizzozERO, Saxer, Kostanecki, Howell, Mondino), or in which 

 the nucleus gradually disappears within the bloodcell (Kölliker, 

 Neumann. Sakfelice, Spuler, Lowit, Eliasberg, Freiberg, GrCn- 

 BERG, Israel, Pappen heim). Disse. summarizing the results obtained 

 up to 1895 writes as follows: „Eine sichere Entscheidung der Frage 

 nach dem Modus der Entkernung der rothen Blutzellen erscheiut 

 einstweilen unmöglich, da die directe Beobachtung des Vorganges 

 der Entkernung im stromenden Blut unthunlich ist." 



On comparing the maternal and tlie embryonic blood-corpuscles 

 as they circulate in each other's immediate vicinity in any section 

 of the preserved placenta of various mammals in various stages of 

 development Ave are struck by two facts. Firstly the nuclei of the 

 embryonic blood-corpuscles differ in many respects from the nuclei 

 of the very earliest bloodcells that arise in the area vasculosa. 

 Secondly it is the first-named „nuclei" and it is not the corpuscle 

 that encloses them, which resemble both in size and very often in 

 staining properties the non-nucleated corpuscles of the mother, so 

 that the question imposes itself whether, if indeed the nucleated 

 embryonic mammalian blood-corpuscles change into non-nucleated 

 corpuscles by extrusion of the nucleus, it might not much rather 

 be this so-called nucleus (which differs notably from a normal 

 nucleus) which will correspond to the definite non-nucleated coi'puscle, 

 than the vesicle from which it has been expelled. 



The observation of quite a different series of phenomena in the 

 placenta cf Tarsius spectrum leads to a confirmation of this hypo- 

 thesis. They render it probable that during the development of the 

 Tarsius-placenta part of the cell-material which is actively concerned 

 in this development, becomes converted into blood-corpuscles that 

 are set free in the circulating maternal blood which bathes it. These 

 bloodcorpuscles, entirely corresponding to those which we encounter 

 everywhere in the maternal bloodvessels, do not take their origin out 

 of the cytoplasma but out of the nucjeoplasma and do not consist 

 of chnnnatin so characteristic for the nucleus, but rather and prin- 

 cipally of nucleolar matter which plays a part in many cell-nuclei 



