LIFE HISTORY OF PINUS 55 



ing in the direction of the nucleus forming a hollow cone over 

 its lower portion (fig. 94, plate VIII). Gradually the granular 

 area increases in density and in staining capacity, at the same 

 time drawing nearer to the nucleus which is separated from it 

 by a hyaline court. Into this court delicate granular threads pass 

 (fig. 95, plate IX). When these threads reach the nuclear mem- 

 brane, the nucleus is forced so closely against the peripheral 

 layer of cytoplasm that its wall is frequently indented on the 

 upper side, while the condensation from which the so-called 

 kinoplasmic threads arise withdraws, or is forced by the growth 

 of the threads, further from the nucleus. A great number of 

 delicate anastomosing threads now extend, in the form of a 

 solid cone, from a point within the granular condensation up 

 towards and against the nucleus. The outer threads of the 

 cone pass over the lower portion of the nucleus and appear in 

 sections of the cell as closely packed against either side of the 

 nucleus. At the same time the entire cytoplasmic reticulum has 

 assumed a more or less radial arrangement about the condensed 

 area in which the spindle-fibers arose and from which some of 

 the more delicate threads extend into the surrounding cytoplasm 

 (fig. 96). 



Coordinately with these changes in the cytoplasm, the chro- 

 matin of the nuclear net collects in spherical or irregular masses 

 on the reticulum, and sooner or later gives rise to a broad spi- 

 reme, along which the chromatic disks are distributed at regu- 

 lar intervals (figs. 94-98). After the segregation of the chro- 

 matin, there remains a delicate achromatic reticulum distributed 

 throughout the nucleus. This reticulum is also granular like 

 the chromatic network, but whether or not these granules rep- 

 resent the oxychromatin-granules of Heidenhain ('93 and '94) 

 I am unable to say. Webber ('01) has recently described and 

 figured a similar achromatic network in the generative cell in 

 Zamia. Whether the formation of the spireme precedes or fol- 

 lows the penetration into the nuclear cavity of the achromatic 

 threads seems to depend upon the length to which these threads 

 attain. They may become very long when their entrance into 

 the nucleus is delayed ; but more frequently a portion of the 

 nuclear membrane gives way, and some of the achromatic 



