356 BULLETIN OF THE 



its origin with the trestle of the quiescent nucleus, or is it a new struc- 

 ture ] In other words, Is there, on the one hand, a complete karyolysis 

 (Auerbach), or a homogeneous condition (Strasburger) 1 or, on the 

 other hand, is there no such stage intervening between the network of 

 the quiescent nucleus and this finer trestle-work 1 If the former were 

 true, then one should at least occasionally find evidence of the existence 

 of entirely homogeneous nuclei. Such is not the case. Instead, one 

 finds on carefully prepared objects nuclei presenting peculiarities which 

 favor the latter view, and for the following reasons: — (a.) Such nuclei 

 present various degrees in the sharpness, compactness, and fineness of 

 the network. The finer and closer the network, the more uniform the 

 thickness of the filaments and the greater the tendency (especially at the 

 periphery) to a sinuous course. (6.) In the quiescent stage the inter- 

 mediary substance (Zwischensubstanz) is capable of staining. In the defi- 

 nite glomerate stage (Knauelstadium) there is no longer any " Zwischen- 

 substanz " capable of being stained. Intermediate conditions, in which 

 this substance has not all disappeared, correspond to intermediate stages 

 in the formation of the characteristic glomerule. This change appears 

 first at the periphery of the nucleus. Flemming, therefore, draws 

 the following conclusion. The first metamorphosis of the nucleus in 

 division consists in this, that the whole of its stainable substance, in- 

 clusive of that contained in the nucleoli and the nuclear membrane, is 

 appropriated for the nuclear trestle, which thereby grows, at first be- 

 coming finer, and extends itself uniformly through the nuclear space in 

 the form of meandering filaments ; it therefore undergoes so complete a 

 metamorphosis, that it is no longer comparable with the trestle of the 

 quiescent nucleus. 



Aside from these changes of the nucleus, the protoplasm of the cell 

 also undergoes changes, (a.) The whole body of the cell passes from a 

 flattened to a more nearly spherical form, — this, however, is principally 

 due to a corresponding change in the shape of its nucleus, — and its out- 

 line often becomes more rounded. (6.) A more important change is an 

 internal one, which exists already in this first stage, — a dicentric arrange- 

 ment corresponding to the future poles of the nuclear figure.* The only 



* I have italicized parts of this last sentence to call particular attention to the 

 early appearance of this dicentric arrangement of granules in the protoplasm of tissue 

 cells. I must grant, it is true, that Flemming furnishes no evidence that this dicen- 

 tric arrangement introduces the changes of division, but that, on the contrary, it is 

 the nucleus itself which first exhibits changes from the quiescent condition. It, 

 however, will not be forgotten that Flemming's attention has naturally been concen- 

 trated on the remarkable alterations in the nuclear substance, whereby the possibility 



