RESEARCHES ON KARYOKINESIS AND CELL DIVISION. 43 



the poles, forming a dyaster^, the strife of the achromatic 

 spindle at the same time becoming visible. The chromatic 

 threads at each pole then fuse together to form the daughter 

 nucleus, which ultimately becomes granular, like the rest- 

 ing nucleus from which the process commenced. The two 

 chief points in which this description of the process differs 

 from Flemming's are — 1st. The division at the equator of 

 chromatic substance previously continuous ; and 2nd. The 

 fusion of threads to form the daughter nucleus. 



On the first of these points Strasbarger is so satisfied that 

 he draws the genera.1 conclusion (op. cit., p. 331) that 

 whatever chromatic element lies in the equatorial plane, or 

 crosses it at the time of division, is divided in the position 

 it happens to have assumed. If there are any equatorially 

 placed threads they are divided longitudinally. The second 

 point is in direct opposition to Flemming's conclusion that 

 the daughter nucleus, in its return to the resting state, 

 passes through the same phases in reversed order as the 

 mother nucleus before division. Flemming has applied to 

 Strasburger's work a crucial test, the result of which showed 

 that the peculiarities in the observations of the latter were 

 due to imperfections in his methods of preparation and exami- 

 nation. Preparations of the protoplasm of the embryo sac 

 ofLilium croceum were sent to Flemming by Herr Soltwedel, 

 whose preparations were in part the material for Stras- 

 burger's work. These had been fixed with alcohol, stained 

 with borax-carmine and methyl-green, and mounted in 

 glycerine. Their appearance under the microscope corre- 

 sponded exactly with Strasburger's figures. Flemming took 

 ofi" the cover-glass from three of these, restained them with 

 alum-carmine, cleared them with oil of cloves, and mounted 

 them in dammar varnish. He then examined them with 

 Seibert's homogeneous immersion r-nih, and Abbe's illumi- 

 nating apparatus, and found that the structure of the 

 nuclear figures was the same as in those from Salamandra. 

 There was no chromatic substance continuous across the 

 equatorial plane, but an equatorial plate formed of two 



1 This term I take from Klein in his 'Atlas of Histology,' 18S0. Plem- 

 ming usually distinguishes the same stage as that of the "Tochter-sterne." 

 It is not to be contused with the nuclear spindle having a polar sun at 

 each end, which, in the ovum of Asterias and other Echiuoderms, precedes 

 the formation of a directive vesicle, and which occurs again in the seg- 

 mentation of the ovum. This appearance, which Auerbach called the 

 " karyolitic figure," corresponds to Flemming's phase showing an equatorial 

 plate. The earlier views on the subject of cell division were put before 

 readers of this Journal in the number for April, 1876, by Mr. Priestley, of 

 Manchester. 



