1Q2 THE BOTANICAL MAGAZINE. t^oi. xxxv. No. 414. 



with Sharp's paper of 1914 the writer is inclined to the view that 

 when condensation together with a somewhat irregular break occurs 

 in the sides of the meshes the reticulate band forms a zigzag or 

 coiled new chromosome, though the details of the morphological 

 relation between the new chromosomes and the meshwork remain not 

 yet thoroughly solved. Figs. 4 and 5 show conditions of this stage. 

 These figures are optical sections and demonstrated sharply only in 

 the central parts of the figure. In Fig. 4 we find a re1;iculate band 

 of an old chromosome running obliquely from the upper left hand 

 side to the lower middle part of the figure, and another one running 

 almost parallel with the former one about in the center of the figure, 

 which shows the beginning of a new chromosome in the upper side 

 of the band. Two other bands running parallel with these reticulate 

 bands are found in the upper part of the right hand side of the 

 figure, these are in a more advanced stage and the formation of new 

 zigzag or slightly coiled chromosomes is seen very clearly, especially 

 in the upper one, a few anastomoses remaining between the other 

 bands. This nucleus is located in a very long cell and there can be 

 no mistake in diagnosing its stage as an early prophase, since the 

 long axis of the cell or of the nucleus and the direction of chromo- 

 somes run parallel to the general axis of the division figure in . the 

 rapidly growing root-tip. Furthermore no nucleus in the correspond- 

 ing stage is found in the surrounding cells. Fig. 5 shows almost the 

 same stage. We find two bands in the center of the figure, the 

 lower one being less advanced than the upper, where the formation 

 of a new chromosome is clearly seen. In these two nuclei all the 

 nucleoli remain quite unstained, so that the presence of the nucleoli 

 does not obscure the details of the band. 



Professor Wilson has kindly given the writer the privilege of 

 studying an excellent preparation of early prophase in a spermato- 

 gonial division of Pbrynotettix, which shows quite the same feature 

 as in Vicia. Inside an old chromosome in the form of a reticulate 

 band, which is a morphological descendant of a chromosome in the 

 preceding telophase (Wenrich,^^ 1916), a new spiral solid chromo- 

 some can be clearly seen (Fig. 6). It is a very interesting fact that 



I) Bull. Museum Comp. Zoology Harvard Coll. Vol. LX. 1916. 



