September, igo6.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



527 



as the single rosette, or "monaster" stage. A most 

 important change now takes place, in that each of 

 tiiese loops splits longitudinally into two equal loops, 

 and the bends of these separate from one another, so 

 that we have finally two systems of loops, arranged so 

 that their bends are remote from, and their free ends 



adjacent to, one another, each system preserving the 

 general rosette arrangement. 



In the next phase observed, these separate systems 

 are travelling away from one another, and the appear- 

 ance we get is that shown in Fig. 7, which represents 

 this stage in one of the cells of the root-tip of the 

 water-lily, with a more advanced stage in an adjacent 



stage), which finally breaks up once more into separate 

 masses of chromatin, which become arranged upon a 

 previously formed linin network. During the^e latter 

 phases, the "cell-plate," or rudimentary partition wall. 



arises in the median equatorial plane of the nuclear 

 spindle. Small thickenings appear at the middle points 

 of the separate threads of the spindle, and these iinally 

 coalesce to form a well-marked cell-plate. VVc have 

 before remarked that this is probaiily an instance of a 

 direct transfornialion of kinoplasm into carbohydrate 

 (cellulose). 



cell. It will be seen that the loops are more or less 

 symmetrically arranged with regard to the spindle. 



When the loop systems have reached the opposite 

 poles of the achromatic spindle, the stage known as the 

 " diaster " .stage is reached, and each of the loop 

 systems then undergoes a series of inverse changes, 

 i.e., the loops lose their symmetrical arrangement, be- 

 come tliinner, and join up to form a spirem (dispirem 



The later stages and the formation of the cell-plate 

 are well shown in I'igs. 8 and g. Fig. g is from 

 a photo-micrograph and the equatorial thicken- 

 ings on the spindle-fibrils can L"e easily distinguished; 

 the daughter-nuclei become further differentiated by 

 the development of fresh nucleoli, and the possible re- 

 sumption of a nuclear membrane. 



It is in this manner that new cells are formed bv the 



