( li^'fi ) 



tho fingeiv-ï it maj" also be sliown that the two iiivagiiiatJous of the 

 bi-concave ditics are not morphologically equal. Their chroniocrateric 

 nature may be rendered visible by „fination" of the out-Howing 

 lilood in osmic acid (according to an observation by Mr. IT. W. 

 Blote, assistant at the Lc}den Laboratory of Physiology). 



We will by no means assert that all nuclei are eliminated by 

 ejection ; there seems to be no reason to question the statements 

 madi' by trustworthy writers of cases in which the nucleus is destroyed 

 by intracellular degeneration. 



In the freshly fixed thighbone-marrow of a Cavia in an advanced 

 stage of pregnancy, a round corpuscle, corresponding in all respects 

 to tiie pycnotic nucleus of mature normoblasts, was observed in 

 nearly all leukocytes next to the polymorphous nucleus. 



Moreover the ejection of the nucleus already figured by Rindfleisch, 

 may be easily observed e.g. in the thighbone-marrow of a rabbit 

 three weeks old. 



Now chroraocraters, corresponding in shape to that described of 

 the Lamprey, vrere also observed by me in Phoxichilidium femora- 

 tum^ a Pycnogonid abounding in the port of Nieuwediep. Also just 

 the same typical exterior of the aboral invagination, sometimes sharply 

 tapering and pointing to the adjacent nucleus. The ejection of the 

 nncleus through the oral opening of a somewhat damaged cell has 

 also been observed. 



I myself have observed chromocraters only in mammalia, lampreys, 

 and the species of Pycnogonid just mentioned. Now we find in 

 zoological literature descriptions and figures by different writers, who 

 probably have seen chromocraters but owing to the difficulty of 

 obtaining living specimens of the sometimens scarce material, their 

 statements could not as yet be controlled or verified. 



Unknown to each other the writers observe with surprise and 

 more or less incidentally, that they have seen bloodcells which 

 were cupshaped. 



DOHRN in his Monograph of the Pantopoda of the Gulf of Napels 

 says, that in nearly all Pycnogonids he had seen bloodcells which 

 he called, „Ballons". „Sieht men sie im Blut circuliren, so erscheinen 

 sie gefaltet, wie ovale Ballons aus Seidenpapier die nicht mit Luft 

 voU erfiillt sind." 



Griesbach^) has figured the haemoglobine-containing cells of Pec- 

 tunculus glvcimeris, a Lamellibranch Mollusc. „Sie sehen miitzen- 



') GniESiiAcii, Beitriigc zur Ilistolosrie des ISlutes. Arcli. f. iiiikroskup. Anntoiiiie. 

 XXXVII. IS'Jl. 



