and Fertilization in the Hemlock Spruce. 593 
irregular and misshapen in outline. It is at this stage that 
the pollen-tube usually enters the neck of the archegonium. 
The Entrance of the Contents of the Pollen- 
tube into the Egg. 
The pollen-tube reaches the egg by penetrating the neck 
of the archegonium, the contents of the neck-cells being 
pressed to one side or swept away entirely. They are fre¬ 
quently found crowded down near the apex of the egg with 
the remains of the ventral canal-cell (Fig. 36). On reaching 
the egg the tube spreads out over it and causes its apex to 
stain diffusely. Further than this the tube itself does not go, 
but the contents of its terminal portion are emptied into the 
egg near the empty vacuole, the membrane of the egg usually 
closing up again, but sometimes remaining open at the point 
of entrance. 
The contents of the pollen-tube thus cast into the egg 
consist of two sperm-cells, the stalk-cell, the vegetative nucleus, 
and some protoplasm and starch from the tube-cavity (Fig. 
36). The stalk-cell nucleus is small, perfectly spherical, and 
conspicuous by reason of its thick, deeply-stained reticulum 
(Fig. 39). The cytoplasm accompanying it is scanty, vacuolate, 
and irregular in outline. The vegetative nucleus is larger, 
ovoid or irregular in outline, and unaccompanied by cytoplasm. 
It contains a delicate network with granules and nucleoli, and 
takes a pale, slightly diffuse stain with Gentian-Violet. 
Above these smaller nuclei lie the ellipsoidal sperm-cells, 
each with dense cytoplasmic contents and a large nucleus. The 
sperm-nuclei differ considerably in size and appearance. The 
one that was in advance in the pollen-tube, which I shall call 
the first sperm-nucleus, is about twice the diameter of its com¬ 
panion, and its contents are so dense that its two small purple- 
staining nucleoli are almost hidden from view. The second 
sperm-nucleus is less dense and shows two large and prominent 
nucleoli that stain a clear red with safranin. It tends to 
conform more to the shape of its cell, and also corresponds 
more nearly to the resting stage than does the larger nucleus. 
R r 2 
