668 SUMMABY OF CURRENT RESEARCHES RELATING TO 



hydra, the nuclear hyaloplasm takes part in their formation. In the 

 embryo- sac of Lilium the amphiaster is visible before the poles act as 

 centres of attraction ; in other cases it originates later. 



When once the nuclear plate is completely formed, the longitu- 

 dinal fission of the chromatic elements commences at the extremity 

 nearest to the centre ; the two halves, separating more and more, 

 glide in the direction of the poles. With complete separation the 

 progressive phases of the division end. This is the stage designated 

 by Flemming metakinesis. 



The regressive phases commence w^ith the movement of the two 

 chromatic groups towards the poles, between which remain the 

 threads of the spindle. In each group the rods form together a 

 radiate figure, the star (etoile) of the daughter-nucleus. Arrived at the 

 poles, the rods contract and curve in various directions, so as to bring 

 their free ends into contact, which then unite so as to form a con- 

 tinuous filament from one pole to the other. Finally, the contraction 

 and reconstitution of the filament is succeeded by the separation of 

 the folds, accompanied by the formation of the nuclear fluid and 

 membrane. The chromatic granula-tions become distinct in the 

 hyaloplasm, at the same time that the nucleoli make their appearance 

 in contact with the folds. The filaments may now remain as such, or 

 may be converted into a new network resembling that of the parent 

 nucleus. 



Changes in the Cell-walls of Epidermal Cells and in the Hairs 

 of Pelargonium zonale.* — In the course of an article on this subject 

 containing a very large amount of detailed observation, Dr. C. 

 Frommann makes the following statements with regard to the inter- 

 cellular protoplasm : — Many intercellular spaces, together with the 

 cleft-like prolongations into which they run out, are so densely and 

 uniformly filled up by granular protoplasm throughout their entire 

 contents, and are, as it were, thus stopped up, that it is impossible to 

 make them absorb water. In cases where the cell-walls are penetrated 

 by threads which connect the parietal intracellular protoplasm with 

 that contained in the intercellular spaces, it is impossible to doubt 

 that the latter has pre-existed as such. There are sometimes small 

 intercellular cavities filled with protoplasm and situated beneath 

 the cut surface, completely surrounded and isolated by cellulose, 

 where there is no possibility of the protoplasm being detached 

 portions which have forced their way in. The granules and threads 

 inclosed in a slightly refractive layer of cellulose by the solidification 

 of the ii^tercellijlar spaces, which are yet distinctly differentiated, 

 show the same properties as those which still lie free in the inter- 

 cellular spaces, Even a,fter the intercellular spaces have become 

 completely solidified, chlorophyll-bodies and denser protoplasm- 

 granules can sometimes be distinguished in them, even when the fine 

 granules and filaments have completely disappeared or become indis- 

 tinguishable. It is evident that in these cases also the protoplasm 

 imbedded in the cellulose must have previously existed free in the 

 intercellular spaces. 



* Jenaisch. Zeitschr. f. Naturwiss., xviii. (1885) pp. 597-665 (2 pis.). 



