54 ^Ir. A. Henfrey on the Progress of Physiological Botany: 
ovule, while he never met with it when the appendix was 
wanting. 
After fertilization, the granular white fluid contained in the 
embryonal vesicle becomes condensed, and appears evidently 
contained in a new cell, which shortly after subdivides into several 
others filled with granules ; then these become extremely multi- 
plied, and thus form the embryo which by degrees comes to 
occupy the whole of the cavity of the nucleus. At the same time, 
the other portion of the embryonal vesicle, that which was in 
contact with the pollen-tube, becomes elongated upward, dividing 
likewise into cells, but into cells which are transparent and situ- 
ated one above another, so as to form a large confervoid filament ; 
this traversing in the opposite direction the course followed by 
the pollen-tube, enlarges and passes through the orifices of the 
tegmen and testa, and becomes prolonged even into the interior 
of the placenta (observed in Orchis mascula). 
The pollen-tube usually disappears during this period, but 
occasionally it may still be seen with its extremity in situ, even 
after the cells of the embryo have been multiplied. It is not rare 
to find it in this condition in Orchis ahortiva, and the author has 
once observed it persistent even to the period when the repro- 
ductive body had filled the whole cavity of the nucleus. 
Orchis ahortiva is better adapted for these observations than 
O. Morio, and particularly for observing the introduction of the 
pollen-tube into the orifice of the tegmen, since in this species 
the state of the ovule at the epoch of fertilization is such that 
the testa only covers the lower half of the tegmen and nucleus. 
O. maculata appeared a less favourable subject than O. Morio, 
but it afforded proofs that the phsenomena were identical in the 
two species. The author imagines that O. 'pyramidalis would 
offer great facilities for these researches, as the ovule appeared to 
him to be extraordinarily transparent ; he was unable to follow its 
entire development, having only at hand a single withered specimen. 
Prof. Amici states directly that he is unable to say what is the 
real action of the pollen-tube upon the ovule in impregnation. 
However he considers it probable, although it cannot be demon- 
strated, that the subtile fluid of the pollen-tube filtrates through 
the membranes into the interior of the embryonal vesicle, and 
that the mixture of the fluids of the male and female organs con- 
stitutes the organizable substance. It is also possible that the 
generative power resides in the membrane of the embryonal 
vesicle, and that the imbibition of the liquid brought by the 
pollen is necessary to set this power in action. Other explana- 
tions of the pheenomena might be offered, the author says, but it 
is not his intention to give himself up to speculation, to lose 
himself in the field of hypotheses. lie adds merely one fact. 
