sjncjiiiim in fig. 14 was sitnaled iiiunediately beneath tlie ependyma, 

 and that in tig. 15 in the dorsal horn of the spinal cord in a 

 jonng wliite monse ten days old. Figures ib, 2a, 3a, 96, 10, 14, 

 15, 16, 17, 18, 19. 20, and 21 are pictures of different stages of 

 young nerve cells engaged in amitotic division. These tigures are 

 all drawn from appearances in the spinal cord of a white mouse, 

 the two first from an animal 24 days old and the others from 10 

 days old animals. In the tnaterial from toads ^nd dogs that was 

 investigated, similar appearances to those in the white mouse have 

 been found to about the same extent. Fig. 9b shows one stage of 

 direct cell division which in my opinion is very rare; I myself 

 have only found this single case. Fig. 20 shows the most advanced 

 incision usually seen. Transitional stages between this and complete 

 division of the nuclei occur exceedingly seldom. I obtained a parti- 

 cularly welcome opportunity thiough Professor Boekk's great kindness 

 during my visit to Holland last summer — of observing in eelem- 

 bryos that it really is a fact that the appearance of amitoses is 

 vei-y rare in cases where the daughter-nuclei show only very narrow 

 communicating bridges between each other. It is, as we know, 

 generally recognized that the nuclei in the myogene tissue increase 

 by direct division during a later stage of its diflferentiation into 

 muscular fibres. Eel-embryos are particularly suitable for the study 

 of this development (Godlewski E. ^). Boeke's very fine preparations 

 of these embryos showed in this region numerous nuclei engaged in 

 amitotic division. It is worthy of note that here too, among this 

 mass of nuclei in amitotic division, no stage could be discovered 

 in which the nucleus showed a far advanced incision — and con- 

 sequently a very small communicating bridge between the two 

 daughter-nuclei. — Accordingly, after studying this material, I was 

 inclined to assume that the last part of the process of division took 

 place rapidly, without any narrow drawn-out communicating bridge 

 between the daughter nuclei being formed. With this in view, it is 

 not strange that I looked u|)on the appearances that form the basis 

 of fig. 21 with a certain amount of surprise and doubt. Does this 

 figure really show stages of amitotic cell division or are they on\y 

 artifical products? The preparations were well fixed and as a matter 

 of fact do not support the idea of there being artificial products. 

 The nucleoli show a particularly great generative tendencj'. If we 



') Godlewski, E. Ueber Kernvermehrung in den quergeslreiften Muskelfasern 

 der Wirbeltiere, Bull, intern, de I'Academie des Scien. de Cracovie. 1900. 



-) Godlewski. E. Die Entwicklung des Skelet- und Herzmuskelgewebes der 

 Saugethiere. Arch. f. micr. Anat. B. 60, 1902. 



