416 MISS М. BENSON—CONTRIBUTIONS TO THE 
find on p. 392 of the English edition the following statement, which, I think, is calculated 
to give an erroneous impression respecting the process of fertilization in Quercus and 
Fagus :—* Fertilization is usually accomplished in a very short time after the pollen-tube 
reaches the apex of the embryo-sac, yet the cases are not few in which a long time 
elapses between the arrival of the pollen-tube and the commencement of the development 
which it excites—several days or weeks in woody plants, as Quercus, Fagus, &c.; almost 
a year in the American oaks, which take two years to тіреп their seed.’ 
It is here implied that the pollen-tube does not enter on its resting stage until it 
reaches the embryo-sac, whereas the organogenetic researches of Baillon show that in 
Quercus no vestige of the ovule is present at the time of pollination, and I have failed to 
demonstrate the presence of tubes in the stylar canal or ovarian cavity until the period 
of fertilization approaches. The tubes remain latent during the four months that the 
ovary is developing in the case of such a species as Quercus Robur, which ripens its fruit 
in one year; but for so long a period as eleven months in other species of Quercus, 
which take two years to ripen their fruit. The case is very similar in the Betuline and 
Corylace:e. 
“In the material which I have examined gathered in 1892, the pollen-tubes remained 
in a resting stage in the case of Corylus from February 5 until June 21, i.e. over four 
ealendar months; in the case of Carpinus, from May 6 to July 1, nearly two months ; 
in the case of Alnus, from March 23 to June 17 , nearly three months ; and in the case of 
Betula, from May 6 until June 8, one month. 
The case of Fagus is particularly easy to investigate. Тһе ovule represented in Pl. LXVII. 
fig. 4 represents the stage reached when pollination occurred оп May 9, but no pollen-tubes 
could be found in the cavity of the ovary until May 21, when they were observed descending 
from the stylar canal in great numbers, and the rapidity of their growth was also curiously 
manifested by a chemical reaction that occurred in material gathered and pickled during 
the week beginning May 91. Large erystals of caleium oxalate were deposited on the 
interior wall of the ovary around the ovules, and often even on the free pollen-tubes as 
they left the stylar canal and entered the larger cavity of the ovary. But even on 
Мау 24 no pollen-tube had reached the nucellus. Three days were required by them to 
find their way down the very long micropyle. The tunnelling of the epidermal cap was 
accomplished only on the last two or three days of May. The embryo begins to elongate 
almost immediately on the pollen-tube reaching the embryo-sac, examples having been 
found of the various stages in material gathered on the same day. | 
In order to investigate whether anything unusual occurred in the young pollen-tube 
which would render it specially fitted for so long а resting stage, Т made several culti- 
_ vations of the pollen-grains of Carpinus and found that they germinated very freely, 
thrusting out the intine at one of the five specially-prepared spots. 
For two days elongation occurred, and then a thickening of the apical region took place, 
and this distal part of the tube became enlarged (Pl. LX ХТ. figs. 46 and 47). Into this 
there passed two nuclei, and the tube not only became plugged at its point of junction 
with the grain, but also I observed it once or twice to be again plugged immediately above 
the enlarged tip, which thus became virtually an isolated spore like a pollen-grain, which, 
