OF TIGRIDIA. 21 
upon its cellular character. Each cell is independent of the 
one above it, that is to say, of the one nearer the pollen- 
grain. The influence of the female organ in thus nourishing 
the male “spermatic tube” is very interesting, and is seen in 
the animal kingdom in the effects of the vaginal and uterine 
mucus upon the spermatozoa. 
The length of the cells of the pollen-tube varies; and it 
appears to me that whenever any difficulty in the passage has 
to be overcome by a little exertion of fresh force the cells 
are nearer together, and that when the passage is free the cell 
is found very long. 
The contents of the pollen-tube, the fertilising agents, are 
granules; these often contain—more especially in the terminal 
cell (Schact noticed this years ago in Pedicularis silvestris) — 
small highly refractile globules, larger masses of filmy looking 
stuff, and the fluid of the tube. This fluid is certainly denser 
than water, for the application of this swells the space between 
the fluid of the cell and the cell-wall. This liquor seminis 
is secreted by the cell-wall of the pollen-tube, after the 
formation of the first cell in the tube; and its individuality 
and specific male properties are not influenced by any length 
or any amount of subdivision into cells. 
In many spots the cell-contents are very scanty, and the 
tube is ribbon-shaped, but the free end of the tube, and 
especially where it passes from the papillose placenta into 
the canal of the micropyle, is cylindrical, very turgid, and 
filled with granular masses and cell-fluid (fig. 5, c). 
I have already noticed that at the time of impregnation the 
Open micropyle is in contact with the papillary structure 
close to the placenta, and it will be as well to observe that 
there is an indubitable vital attraction between the end of the 
pollen-tube and the micropyle of the ovule, quite as great as 
there is in many plants between the anthers and the stigma. 
Once within the canal of the micropyle, the pollen-tube is 
nourished by the contiguous cells of the nucleus ; and here a 
cell is usually added to the pollen-tube, and oftentimes two. 
The free end, completely fillmg the canal of the micropyle 
(fig. 7, a, 6), passes onwards, and as the nutrition of 
the cells of the nucleus is active, so is its progress rapid; it 
impinges, at last, against the anterior convex cellular wall of 
the embryo-sac. The progressive force still continues, and 
the terminal cell of the pollen-tube presses the embryo-sac, 
at the point of contact, backwards, until, at last, the end of 
the pollen-tube-cell is hidden by the wall of the embryo-sac.* 
* This was well shown by Schleiden, but he mistook the bulbous end for 
the embryo. 
