POLLEN-BODIES OF THE ANGIOSPERMS. 
27 
5 per cent, strong, six hours). The nuclei travelling into 
them are thereby elongated and become altogether similar 
to one another (fig. 25). 
Narcissus poeticus . — Here the development is precisely 
similar, only that the vegetative cell is more spindle shaped, 
almost like that in Ornithogalum. 
r obtained Pollen-tubes of N. poeticus after four hours’ 
cultivation in a solution of 3 — 5 per cent, of sugar. In 
general, the nuclei, as soon as they have entered the tubes, 
cannot be distinguished, as they have become elongated early, 
often even in the Pollen-body (fig. 26). In many cases, how- 
ever, viz. where the nucleolus of the nucleus belonging to the 
larger cell was still preserved, I was able to determine with 
certainty that sometimes the nucleus of the vegetative cell and 
sometimes that of the large cell went in front. I once saw, 
what is very exceptional, the doubling of the posterior nucleus 
(fig- 
Iris sihirica is very difficult of examination owing toe 
the richness of the cell contents and the thickness of th 
extine. The extine can be removed and the conditions of 
the investigation made easier if the Pollen-bodies are put 
into a drop of water or of sugar solution, and the covering 
glass is repeatedly raised up and down by means of a pair 
of small pincers. By such manipulation the extine will 
separate from several Pollen-bodies. If the Pollen-bodies 
of older buds are subjected to this treatment it is sometimes 
possible to press the whole contents of the large cell out, 
so as to leave the small vegetative cell attached to the intine 
(fig. 29). It must, therefore, be surrounded by a tolerably 
resisting (cellulose?) membrane, and I actually succeeded 
once in demonstrating such a membrane by a cautious 
crushing (fig. 28). The vegetative cell is always formed on 
the flattened side of the Pollen-body. Its nucleus has a small 
nucleolus, the nucleus of the larger cell is a little larger and 
has also a larger nucleolus. In the ripe Pollen-body the 
two nuclei are almost unchanged, the vegetative one is some- 
times naked and sometimes covered with a hyaline proto- 
plasmic mass of a spindle shape, which represents the 
vegetative cell set free. 
Pollen-tubes were obtained after a cultivation of six hours 
in a solution, 30 — 40 per cent, strong, of sugar. As soon 
as the tube formation begins all signs by which one can 
distinguish the two nuclei vanish. They travel rather 
late, and often beside one another into the wide tubes, and 
can then only be pointed out as bits of protoplasm, coloured 
deeper than the rest by carmine, which have no clear outline. 
