Genetic Eelation of Neurofibrillae to Chromatin. 81 



111 the most instructive cases it is to be reg-retted that a position 

 of a given structure of the desired sort properly adapted to decent 

 photography is generally a relatively rare accident. 



That the nucleus in Fig-. 2 is in the act of protruding- at least 

 three bundles of parallel, more or less independent chroniofibrillae 

 is the only logical conclusion in view of the observations on anal- 

 ogous cases. But whether such chromofibrillae, in this particular 

 instance, are destined to become neuroglia fibers or neuroflbrillae 

 w^e may consider for the sake of argument as a matter of opinion. 

 Neuroglia forms the subject matter of a contribution to be published 

 in the near future. 



In consideration of Fig. 3, from the grey matter close by the 

 previous nucleus, a pronounced expression of the same purposive 

 differentiation, so to speak, of the chromatin into chromofibrillae is 

 the feature of immediate attraction. It is however quite unnecessary 

 to conclude that it concerns itself here with the development of 

 neuroglia fibers for this happens to be the nucleus of a uni- 

 polar ganglion cell. As evidence, or better proof of such the 

 neuroflbrillae and Nissl substance in the cytoplasm suffice. To 

 interpret this figure in the reflected light of numerous others, it 

 seems plausable that the chromofibrillae which are merg- 

 ing in the form of a bundle from the nucleus of the 

 ganglion cell constitute the forerunner of a nerve 

 fiber which would render the unipolar ganglion cell 

 bipolar. Evidently upon the completion of such — upon final 

 emancipation from the chromofibrillae, now neurofibrillae — the 

 nucleus has a tendency to resume the general form corresponding 

 to that of Fig. 1. 



Fig. 4 is a Puekinje cell from the cerebellum of the same 

 Salamandra maculosa. Were not the stain especially rich in contrast 

 there would be perhaps nothing extraordinarily noteworthy to be 

 observed in addition to the much discussed socalled polarity of the 

 nucleus. But this same nucleus is guilty of something. There is 

 still a number of very distinct chromofibrillae hanging to it. They 

 have not as yet been fully emancipated from the nucleus, which 

 seems to be just in the act of retiring to "private life". But for 

 the sake of merely casual observation it is a Purkinje cell with a 

 conspicuously thick neurite which contains in the normal manner its 

 neurofibrillae. 



Fig. 5 may be interpreted as a "before and after" group. The 



Zool. Jahrb. XXXIX. Abt. f. Anat. 6 



