POLLEN-BODIES OF THE ANGIOSPERMS. 
33 
Of the other Cyperaceee examined Carex vulpina and 
Cyperus hadius are, perhaps, less suited for examination 
than Heleocharis. I can, however, state with certainty that 
in all the development is precisely similar. 
I have intentionally fully discussed the stages of develop- 
ment in the Monocotyledons. These can generally be more 
clearly seen in them than in the Dicotyledons, in which the 
richer contents of the cells and the small size of the nuclei 
make the examination more difficult. Besides, the Dicoty- 
ledons show nothing extraordinary ; nothing w'hich does not 
also occur in the Monocotyledons. I can, therefore, record 
my observations of them in a small space. 
In the Pollen-bodies of the Dicotyledons we know that in 
general many orifices in the extine are formed. This, to- 
gether with the more or less spherical shape of the Pollen- 
bodies, makes it impossible to indicate the place where the 
vegetative cell is formed with the exactness that one could 
do in the Monocotyledons. In the ellipsoid Pollen-bodies of 
the Papilionaccse and Umbelliferse, where the orifices for the 
tube are formed in an equatorial circle, the vegetative cell 
occupies a polar position. Even in the case of other Dico- 
tyledons the position of the vegetative cell was never ob- 
served just under the extine orifices. Nevertheless, it seems 
to be the large cell that grows out to form the tube. 
The vegetative cell is separated by a more or less convex 
partition wall of cortical plasm from the large cell. Its 
nucleus and nucleolus are always smaller than the same 
parts in the large cell. 
Th® vegetative cell soon separates from the intine and 
appears as a spherical formation free in the Pollen-body. 
As in many Monocotyledons, a division of the vegetative 
nucleus can still take place ; so that three nuclei are pre- 
sent in the ripe Pollen-body. This occurs in Samhuctis 
race77iosus, Fedia cornucopicB^ Dahlia Merckii^ Nymphaea 
alba, Biscutella eidgerifolia, Gei'aniu^n Hookerianum, A 7 'e?i~ 
aria laricifolia, Foeniculum officinale. 
The two vegetative cells resemble one another, and after 
a time have no nucleoli. 
In Nymphaea alba the nucleus of the large cell gene- 
rally preserves its nucleolus in the ripe Pollen-body, often 
even in the tubes (1 — 5 per cent., twenty hours). I can 
certify that this nucleus goes into the tube earlier than the 
two other vegetative ones which lie beside one another. It 
was only on very rare occasions that the opposite order 
obtained. 
In the other plants mentioned above, the three nuclei can- 
VOL. XX. NEW SER. C 
