352 BULLETIN OF THE 



which is a preliminary report on the results of studies upon the structure 

 of the cell and upon the phenomena of cell division. He maintains in 

 all essentials the views previously expressed (see p. 264) concerning the 

 structure of the quiescent nucleus. 



As this was not received till after his final paper (Flemming '78'') had 

 been reviewed, the reader is referred to the account of the latter on 

 page 355. 



Schleicher (78")* recognizes in cartilage cells capable of, but not 

 undergoing division (Theilungsfahig), fibres, rods, and granules in the 

 protoplasm outside the nucleus. The fibres are rectilinear or curved, 

 often radially disposed, at other times concentrically arranged about the 

 nucleus, etc. The rods are shorter than the fibres, but are also often 

 radially disposed. The granules are most abundant near the nucleus. 

 All of these elements exhibit lively amoeboid motion, while the nucleus 

 shows as yet no differentiation. This quiescent nucleus is either ho- 

 mogeneous with one or two clear nucleoli, or, if less homogeneous, it is 

 doubtless owing to an approaching or just completed division. For 

 Triton, however, the presence of coarse granules and rods in the nucleus 

 is Q. permanent feature. But such structures do not necessarily involve 

 the assumption of a connected network, against the existence of which, 

 either in nucleus or protoplasm, the author urges the great activity of 

 the structures in question. Their supposed existence and the union 

 of intra- with extra-nuclear networks are referable to the employment 

 of reagents. The histologist must confine (!) himself to the living 

 cell in studying these phenomena. Since, in the author's opinion, all 

 those structural peculiarities of the nucleus known as fibrous mass, gran- 

 ular mass, rodlike structures, stellar figures, glomeruli, etc. are only in- 

 terchangeable appearances of the same thing, viz. " nuclear substance," 

 he would designate the whole series of phenomena under the head of 

 *' Karyokinesis " (nuclear motion). In the formation of the karyokinetic 

 figure participate granules and rods (when previously existing), nucle- 

 olus, new diff'erential products, and the dismembered nuclear membrane. 

 No change of dimension either in nucleus or cell heralds the approach of 

 the division. The karyokinesis consists in a series of rearrangements of 

 the nuclear substance without predetermined order, in which more or 

 less regular figures are preceded and followed by such as are altogether 

 irregular. These rearrangements are accompanied by the disintegration 

 of rods into granules, and the reverse process. These changes — intro- 

 ductory to the real act of nuclear division — take place with varying 



* See also Schleicher '78. 



