20 6 Ferguson . — Development of the Pollen-tube and the 
the extreme upper portion of its cell, certain changes in the 
cytoplasm indicate that division is being initiated. At some 
little distance below the nucleus the cytoplasm shows a finely 
granular structure which is not at this stage dense nor deeply 
staining. From this region irregular granular threads arise 
which extend outward towards the periphery of the cell, 
those extending in the direction of the nucleus forming a 
hollow cone over its lower portion (Fig. 23). 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. 24). When these threads reach 
the nuclear membrane, the nucleus is forced so close 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 delicately 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, into which some of the more delicate 
threads extend (Fig. 25). 
Co-ordinately with these changes in the cytoplasm, the 
chromatin of the nuclear net collects in spherical or irregular 
masses on the reticulum 3 and sooner or later gives rise to 
a broad spirem, along which the chromatic disks are distri- 
buted at regular intervals (Figs. 23-26). Whether the forma- 
tion of this spirem precedes or follows 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 mem- 
brane gives way, and some of the achromatic fibres pass into 
