LIFE HISTORY OF PINUS 123 



and interrupted, granular, achromatic network which is crossed 

 by several coarsely granular, deeply staining threads. These 

 threads, which represent the chromatic portion of the nucleus, 

 have at first no definite arrangement ; but they soon unite to 

 form two distinct, coiled or angled spiremes, which draw to- 

 gether at one side of the nucleus (figs. 244, 245). It is an 

 interesting fact that these spiremes are always found on adja- 

 cent sides of the two nuclei. This position suggests that there 

 is a certain attraction, comparable to that existing between the 

 sexual nuclei, active between these nuclei ; or the relation of 

 the inner sides of these nuclei with the poles of the spindle, in 

 the early stages of their formation, may have some influence 

 upon the position which these spiremes assume in the dividing 

 nuclei. 



When the two spiremes, which are still roughly beaded with 

 the chromatic substance, come to lie side by side along the inner 

 wall of the nucleus, the nuclear wall resolves itself into a weft 

 of fibers. These threads pass into the surrounding cytoplasm 

 and soon wholly disappear, while, at the same time, achromatic 

 fibers arise in the regions of the spiremes (fig. 245). The 

 achromatic threads quickly draw together, forming a sharply 

 bipolar spindle on which the two now perfectly homogeneous 

 chromatic bands lie. The spindle does not become bipolar in 

 some instances until after the segmentation of the spiremes 

 (figs. 245-247). I have preparations representing a complete 

 series in this division, but, as it is exactly similar, especially in 

 its later stages, to the first division, it is not thought best to 

 multiply sketches by repeating like figures. 



There can be little doubt that the two spiremes formed in each 

 of these nuclei represent the separated-out paternal and maternal 

 chromatic substance, although to all appearances, the chromo- 

 somes were completely fused in the reticula of the daughter- 

 nuclei. One is reminded by these phenomena, of Strasburger's 

 ('92) remark, when he states that he accepts the view of a com- 

 plete fusion of the segments into a network in the daughter- 

 nuclei, and then asks if he must, therefore, conclude that the 

 chromosomes in the following divisions do not correspond in 

 material. This restoration of the paternal and the maternal 



