385 



Tangl observed that iu the scales of Allium sepa the nuclei 

 always gathered at the points where the cells had been injured and 

 the same was observed in Vaucheria by Haberlandt. 



May we not likewise interpret the movements of the nuclei of the 

 muscle cell as of physiological significance and subscribe to the follow- 

 ing words of Yves Belage: "Lorsque, dans une cellule, les pheno- 

 menes d'accroissement sont plus actifs dans une region, le noyau se 

 rapproche de cette region et Ton pent presque dire que I'intensit^ de 

 I'accroissement en un point est une fonction directe de la distance de 

 ce point au noyau." 



Having thus emphasized the nuclear changes and their apparent 

 correlation with phases of cytoplasmic activity we are naturally led 

 to ask if the nucleus of the muscle cell, like that of the gland cell, 

 builds up and gives off chromatic material which plays an important 

 role in cytoplasmic metabohsm. 



In the muscle cell there is one structure which possesses the 

 characteristic staining properties of chromatin, namely, the dark band 

 of the muscle fibril. Although thus far I have been unable to trace 

 nuclear chromatin into this band, it is a tempting hypothesis and in 

 perfect accord with the phenomena observed in gland cells to suppose 

 that it is thus derived. Moreover we are in possession of certain 

 facts which strongly support such an hypothesis. 



Micro-chemical tests made by A. B. Macallum show that the 

 dark band contains an iron holding nuclein. The author states that 

 in the cells undergoing transformation into striated fibres some of the 

 chromatin dissolved in the cytoplasm (from the yolk granules) finds 

 its way into the nucleus, as in other cells generally; but the greater 

 part appears to remain in the cytoplasm of the developing fibre where 

 it later passes into the darker band of the fibril. The author ex- 

 plicitly states that he regards this process as exceptional. In general 

 the chromatin derived from the yolk granules is converted into nuclear 

 chromatin. 



Another objection to Macallum's interpretation is the fact that 

 in the regeneration of the adult muscle fibril the dark bands appear 

 in the absence of yolk granules. 



Again we find that the regeneration of the muscle fibril is pre- 

 ceded by a great increase in the quantity of chromatin which has 

 been brought about through repeated division in the injured end of the 

 muscle cell. This process being in perfect accord with the hypothesis 

 which I have offered. 



Anat. Anz. 2X1. Aufsätze. 25 



