80 GrAYLORD SwiNDLE, 



of exactly how, when and where, above all of course how, in this 

 given mass of protoplasm, the building of the fibrillae takes place. 



While the neurofibrillae present specific chemical and morpho- 

 logical differences to the cytoplasm in which they are imbedded, a 

 noteworthy similarity, on the other hand, to nuclear material is 

 often sufficientl}' conspicuous to have occasioned at times the ten- 

 dency to assume a more or less remote genetic relation to chromatin. 

 The purpose of the present contribution is that of strengthening the 

 plausibility of such an assumption. 



Let us next interpret the illustrations in the accompanying 

 plate. The Fig. 2 is a nucleus, possibly yet not at all necessarily 

 of a ganglion cell, from the central grey matter of the spinal cord 

 of an adult fire salamander, Salamandra maculosa. The feature of 

 immediate interest is the short, branched pseudopodial outgrowth 

 which consists internally for the most part of parallel fibrillae of 

 chromatin (chromofibrillae should we choose to designate them thus.) 

 The thickness of the nucleus, however, together with its marked 

 obliquity in position, and in addition the abundance of neuroglia 

 and nerve fibers above and below it in the section of 80 ju, exclude 

 the possibility of adequately demonstrating the fibrillae photographi- 

 callj". The rear portion of the nucleus consists primarily of plastic, 

 massive chromatin. It is first in the middle region that a gradual 

 mergence from homogeneity into heterogeneity begins. The fibrillae 

 assume their form as such so gradually that a definite line of 

 demarkation is scarcely distinguishable. As they are tunneled into 

 the protruding bud the contour of the individual fibrillae becomes 

 increasingly even and parallelism more marked. Lateral buds, 

 structurally identical with the primary stalk, disfigure the contour 

 of the latter. Chromofibrillae from all parts are focused into these 

 secondary outgrowths. They are fed in part by branches arising 

 from the main fibrillae. 



One is confronted by mau}^ questions in consideration of the 

 figure just mentioned. First of all, what is the fate of such morpho- 

 logical differentiation? What is the maximum length and maximum 

 independence to be attained by chromofibrillae thus formed? In 

 preparations of the proper sort it is a matter of relative simplicity 

 to establish as a fact that many such may attain a length exceeding 

 that of the original nucleus by many thousand times. It is to be 

 regarded as a matter of course that the accompanying figures are 

 interpreted primarily in tiie light of an enormous number of others. 



