and Fertilization in the Hemlock Spruce. 589 
dividing vegetative nuclei and the nuclear membrane (Fig. 15). 
In later preparations this area seemed to have broadened and 
filled with delicate threads (Fig. 18) which later drew together 
above, but I cannot be sure of this 1 . Possibly the collection 
of sap is so small that it often disappears in fixing. Careful 
search was made for a similar collection at the lower pole, 
but without success. 
The further development of the spindle is very rapid. The 
nuclear membrane disappears below and the spindle-fibres 
press into the nuclear cavity and connect with the linen net¬ 
work, already partially arranged in such a way as to continue the 
fibres to the chromosomes or through the centre of the cavity. 
The fibres soon become homogeneous below, while at their 
upper extremities they are still only rows of granules (Fig. 21). 
Nothing now remains in the nuclear cavity except the spindle- 
threads and the homogeneous chromatin segments. The large 
spreading bundle of fibres originating from below traverses 
about two-thirds of the nuclear cavity before connecting with 
those from the upper pole. The nucleus consequently becomes 
pear-shaped at this stage, with the upper end larger. As the 
spindle-fibres draw in towards the centre, the chromosomes 
are forced from their peripheral position and come to lie along 
the central part of the spindle (Fig. 23). At the same time 
the upper pole is somewhat elevated and appears as an abrupt 
but sharp point rising out of the nuclear cavity. Supporting 
fibres run from this pole to the cell-wall and in various 
directions through the neighbouring cytoplasm (Fig. 35). 
In the plate-stage (Fig. 26), the chromosomes show the 
form and arrangement characteristic of that class of divisions 
recently denominated £ typical' by Strasburger (1900), and 
1 It is often impossible to demonstrate the existence of an extra-nuclear spindle- 
rudiment at the upper pole, but the fibres appear to collect in bundles within the 
membrane and to unite at one point when the polarity becomes more pronounced. 
The narrowing and consequent stretching of the spindle as the metaphase is 
approached would elevate the upper pole and give it the appearance of penetrating 
the membrane (Fig. 22). In Larix Americana there is still less cytoplasm above 
the nucleus than in Tsuga, which makes the difference in the two poles yet more 
marked. 
