406 



L. DONCASTER 



stance may be in part at least due to the technique of fixing 

 and staining. 



iSeiler has no doubt that the stained matter in the ehmina- 

 tion plate is chromatin, and reviews the literature of maturation 

 divisions of insect eggs, and also such examples of chromatin 

 elimination as those seen in the segmentation of As car is 

 and Miastor, in order to discuss the significance of the pro- 

 cess. He does not, however, discuss at all fully the question 

 whether the substance eliminated is in fact chromatin, or if 

 it is, whether it is of the same nature as the chromatin of the 

 anaphase chromosomes. His account of his staining methods 

 is meagre — ' (iefiirbt wurde vorwiegend mit Heidenhains 

 Eisenhamatoxylin und Kontrollfiirbungen wurden mit Kern- 

 farbstoff(3n vorgenommen. Als Plasmafarbstoff verwendete 

 ich S.-Fuchsin ', Unless the elimination process is in reality 

 an artefact, which seems very unlikely in view of the almost 

 invariable presence of staining granules in the equator of the 

 spindle and the definite manner in which they appear to be 

 left behind by the diverging chromosomes, it appears to be 

 of considerable importance to determine the true nature of the 

 eliminated substance, for if it be chromatin, it seems not 

 impossible that the process may supply the clue to the anomaly 

 presented by the presence of twenty-eight chromosomes in 

 eggs which nevertheless vield females. If the chromosomes 

 do in fact leave behind on the polar spindle a considerable 

 part of their substance, it is at least conceivable that the sex- 

 chromosome, in the eggs of all-female broods, eliminates so 

 much that it becomes functionless as regards sex-determination, 

 and that, having lost so large a part of its substance, it ceases 

 to function and disappears, so that in the oogonia only fifty- 

 five instead of fifty-six can be counted. With the object of 

 determining whether the elimination plate does or does not 

 consist of chromatin I stained eggs with a number of com- 

 binations of stains, the more important of which were as follows : ^ 



[All the sections used had been previously stained with iron 

 haematoxylin and were decolourized with acid alcohol.] 

 ' Professor Doncaster"s manuscript ends here. 



