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1905] SHOEMAKER—HAMAMELIS VIRGINIANA 255 
It is also probable that this part of the nucellus forms the extremity 
of the conducting tissue for the pollen tube. In early stages 
three to five macrospores can be seen, but only one germinates. This 
goes through the usual stages, the resulting nuclei being arranged in 
the order most often found among angiosperms (fig. 10). The antip- 
odals very early disappear, so that they are hard to find at the time 
of fertilization. The endosperm nucleus is found about the middle 
of the sac. 
The tissue surrounding the mature embryo sac is much disinte- 
grated (jig.r0). Around the chalazal end of the sac the tissue always 
stains deeply, and there is a quite evident strand of conductive tissue 
from the tip of the fibrovascular bundle at the chalaza to the lower 
end of the embryo sac (fig. 10). The base of the nucellus shows by its 
smaller cells that it is the most rapidly growing part. The develop- 
ment which the ovule has attained at the beginning of winter is shown 
in fig. rz. The integuments up to the early part of April are still 
behind the nucellus in growth; in spring their growth is hastened and 
they soon project beyond the nucellus, leaving a wide open micropyle 
(fig.21). This is finally closed to a slit-like fissure between the edges of 
the outer integument. 
The outer integument is now quite thick, formed of about eight 
layers of cells, and is uniform in structure throughout. The inner 
integument is made up of three layers of cells which are very much 
alike. The epidermal layer of the nucellus has already become 
slightly different from the underlying tissue. 
POLLEN TUBES ARTIFICIALLY GROWN. 
Pollen taken from open anthers was very readily sprouted in a 16 
ber cent. sugar solution made with tap water, in which 1.5 per cent. 
gelatin was dissolved. The pollen grains first became spherical by 
, € filling out of the furrows, thus using the masses of intine on the 
tner sides of the furrows. Tubes sprout from the pollen grains when 
Placed in the nutrient gelatin in one to three hours, and always 
arise from the smooth bands. The cultures were kept at room tem- 
Perature and growth was more luxuriant in the dark. The growth 
of molds, etc., usually disturbed the cultures at the end of a few days. 
The behavior of the nuclei was not readily observed. Methyl- 
Steen-acetic-acid was used to kill the pollen tubes, and no more 
