350 BULLETIN OF THE 



of the frog's cornea only by the presence of a distinct radial arrangement 

 of the granules in the cell protoplasm. The processes in the epithe 

 lium of the tail of the fish embryo were essentially as in the epithelium 

 of the frog's cornea. The Kernplatte were distinct, and appeared after 

 division like two combs with the teeth turned toward each other. 



In the case of Triton the division is similar. The granules and fibres 

 of the modified nucleus are remarkably thick.* After division the nu- 

 clei take the form of fibrous baskets destitute of bottoms, and when 

 stained in picrocarmine appear like " gayly colored flowers." The nu- 

 clear plate is wanting. The staining of the fibres in picrocarmine and 

 their failure to do so in osmic acid are evidences to the author that they 

 are simply modified nuclear substance. This reaction, coupled with the 

 contrary deportment of the remnants of " Dotterpliittchen " to be found 

 in the larva of Triton, is sufficient proof of the inaccuracy of Torek's 

 conclusion, that similar filamentous structures in Siredon arise by a 

 metamorphosis of the Dotterplattchen. Moreover, the nuclear division 

 is of the same nature in the fully developed Triton, where 710 Dotter- 

 plattchen are present. 



Further, the direct observation of division in living cells and nuclei 

 (epithelium of Triton larvse) is possible. Two cells were seen to divide 

 in the course of ten minutes, in one case by an advancing constriction, 

 in the other by means of the formation of a row of small vacuoles in the 

 equator of the cell. The nuclei were already divided, and appeared in 

 the form of a basket composed of dull lustrous rods conically arranged. 

 The rods become shorter, first growing more slender at the equatorial and 

 thicker at the peripheral end, and finally fuse into an irregular knobbed 

 mass. These changes of nuclear form cannot be called amoeboid. f 



Strasburger (77, pp. 519-521, Taf XXXIIL Figs. 56-71) has in- 

 troduced into this paper several figures of Mayzel's preparations illus- 

 trating division in the tissue cells of animals. The elements of the 

 nuclear plate (Figs. 56-58) from endothelium of the frog's cornea ex- 

 hibit the same arrangement (outside the spindle fibres) which Strasburger 

 pointed out as sometimes existing in Nothoscordum. A well-marked 



* Compare Strasburger ('77, Taf. XXXIIL Figs. 64-71) where Mayzel's prepara- 

 tions are figured. 



t See also Mayzel '77 and a review {'77^) by the author himself in "Hofmanii u. 

 Scliwalbe's Jahresbericlit," etc. 



P. S. — Another more extended paper by Mayzel ('78) is inaccessible to nie, and 

 the short notice (Mayzel, '78") given of it in the Jahresbericht of Hofmanu and 

 Schwalhe is too brief to be of any value. A review of the whole is promised wl:eji 

 the second part has been published. 



