38 J. T. CUNNINGHAM. 



equatorial plane a figure which may be compared to a 

 shallow basket, or half-opened daisy, with its opening 

 opposed to that of its fellow. These " baskets " now begin to 

 recede from one another, revealing often in the interval 

 between them delicate faint strise which represent the achro- 

 matic " nuclear spitidle " so conspicuous in the dividing 

 nuclei of the endosperm in Phanerogamia (vide Strasburger, 

 ' Zellbildung u. Zelltheilung,' 1880, Taf. i). When they 

 are separated for a certain distance the baskets open out 

 into stars forming the " dyaster " (fig. 10). The cell mean- 

 while begins to show an equatorial furrow, by the deepening 

 of which it is divided into two daughter cells, each contain- 

 ing a daughter nucleus. The daughter " star " becomes con- 

 verted into a " wreath" by the junction of the ends of the 

 loops to one another ; the wreath passes into a " convolu- 

 tion," and this into a " reticulum," while a membrane appears 

 round the daughter nucleus, nucleoli are formed, and the 

 ground substance again becomes affected by dyes. This 

 inverse metamorphosis is shown in figs. 11 — 15. 



From the part played by nucleoli in this series of changes 

 Flemming concludes that they are merely accumulations of 

 chromatin to form a reserve, which is drawn upon for the 

 formation of fibrils at the commencement of karyokinesis. 

 This view, as he points out, is opposed to all attempts to show 

 a connection between nucleoli and the ultimate branches of 

 nerves. 



Relation of Ifnclear Network to Cell-body. — The intimate 

 structure of the nucleatetl cell in its resting state is a 

 matter on which observers are still at variance. Klein holds 

 that the cell is composed, like the nucleus, of a reticulum and 

 an intermediate substance, or ground substance, which fills 

 up the meshes of the reticulum ; and that the trabeculae of the 

 nuclear reticulum are directly continuous with those belong- 

 ing to the cell. Flemming, in his latest work, has made some 

 extremely interesting observations on the structure of the 

 resting nucleus. By the help of Seibert's homogeneous 

 immersion and Abbe's illuminating apparatus he has dis- 

 covered a definite structure in the intermediate substance, 

 which had previously appeared smoothly stained or finely 

 granular. He found in it a much finer network of stained 

 fibrils in connection with the coarse, well-stained trabeculae 

 already known ; the fine granulation shown in the ground 

 substance by weaker lenses is the optical expression of the 

 fine network when not resolved. He thinks it probable, 

 though he was unable to determine the fact absolutely, that 

 the substance occupying the meshes of the finer network 



