No. 3-] STUDIES ON THE HETERONEMERTINI. 411 



diesen Fortsatz uberhaupt, jedenfallsaber sein verjiingtes Ende 

 sehr an Dicke iibertrifft " (p. 334). The " Nervenfibrillen " of 

 all cells but IV possess " Nebenfortsatze " : " Unsere Neben- 

 fortsatze entspringen von den Verdickungen [varicosities] der 

 Fibrillen. . . . Ich halte den Stammfortsatz der Ganglienzelle, 

 obwohl ich an ihm zwei Abschnitte [" Ganglienzellfortsatz," 

 " Fortsatzfibrille "] unterschied, keineswegs fiir ein zusammen- 

 gesetztes Gebilde im Sinne von Dohrn ['91, the view has since 

 been relinquished by Dohrn] und Apathy" (p. 335). 



Now the Gottingener investigator distinguishes on the "nerve 

 fibre": (i) the true prolongation of the ganglion cell, and dis- 

 tally (2) the " nerve fibril," which he claims is sharply bounded 

 off from the former, though both should stand in the same 

 genetic relationship to the cell ! He found, with the intra 

 vitam methylene blue staining, that the distal " Fibrille " stains 

 more intensely than the proximal "Ganglienzellfortsatz"; he 

 gives no structural details of its formation, but his term 

 "Fibrille" leads us to suppose that he conceived of it as a 

 dense fibril with a structure different from that of the proximal 

 process. His descriptions would give the idea, further, that 

 there is an abrupt local as well as structural demarcation 

 between the two, i.e., that they do not merge gradually into 

 each other. Already in a former paper Burger ('90b) had dis- 

 tinguished ganglion-cell process and nerve fibril on the study 

 of sections fixed with chromic acid and with alcoholic subli- 

 mate (.''); of the structure of the ganglion-cell process, he states 

 (p. 112): " Bei HI und IV ist das Paramitom vorherrschend. 

 Es ist in mehreren Saulen im Fortsatze gelagert, jede Saule 

 wird von einer Mitomscheide umgeben, das gesammte Biindel 

 umfasst eine besonders kornige Mitomschicht, wie sie als 

 Rindenschicht des Zelleibes charakterisirt wurde." This 

 representation of the structure of the proximal portion of the 

 axis cylinder, namely, as a nerve tube composed of a bundle 

 of "primitive nerve tubes," is in close accord with the descrip- 

 tions of Nansen ('87) for other forms; and Burger's Fig. 56, 

 Taf. IV, bears marked resemblance to certain of Nansen's 

 figures. Finally, of the nerve fibril, he states ('90b, p. 118): 

 "Als Formelement der centralen Fasermasse habe ich eine 



