128 DR. H. CRUGER ON THE FECUNDATION OF ORCHIDS 
female flower, mixed with a large quantity of sweetish mucosity. 
This secretion, while it probably causes the disaggregation ot 
the cells of the conducting tissue, has the property of separating 
the pollen-cells when these latter are brought into contact with it. 
I could not, however, discover any difference in this respect be- 
tween the pollinia of male and female flowers, for both were acted 
on in the same way; but there the resemblance ceases. Left a 
little longer in contact with this mucosity, the pollen-cells of the 
male push forth a vigorous vegetation of pollen-tubes, while from 
the pollen of the female only here and there a rudimentary tube 
may be seen. 
I would here remark, that this action of the sweet mucosity on 
the cohering tissues of the pollen appears to me to belong to the 
phenomena of fermentation, in its wider sense. The same effect 
is produced by substances in a state of decomposition, and may be 
compared in some manner to the ripening of fruit. It must not, 
however, be confounded with the action of boiling on certain 
tissues of roots, where it is explained, according to recent researches, 
by the conversion of the outer layers of cells into pectose, which 
is rendered soft by boiling in water. 
Although I have tried, like others before me, repeatedly to 
impregnate a male flower with its own pollen, I have always 
failed. The incomplete development of the conducting tissue 
explains this sufficiently. On the other hand, the operation never 
fails with the female flower when male pollen-masses are applied 
to it at the proper moment. The action of female pollen is at first 
not to be distinguished from that of male pollen, but until now 
I have not seen a case of complete success. The ovarium enlarges, 
the labellum &e. fade, pollen-tubes are emitted; but after a week 
or so the ovarium begins to fade, turns yellow, and finally drops, 
without bringing any seeds to perfection, or even without fecun- 
dation taking place. 
Many years ago, when specially occupied with the more inti- 
mate phenomena of fecundation in plants, I pointed out (Bot. 
Zeitung, 1851) that pollen, besides giving the material foun- 
pation (sit venia verbo) for the pollen-tubes, has an evident 
power of stimulating a flower to development—to the production 
of ovules or their perfection. Dr. Hildebrand has lately (Bot. 
Zeitung, 1863, Nos. 44 & 45) published detailed observations on 
this subject, without however stating anything not previously 
known. Does not the female pollen of Catacetwm possess only 
one-half of the functions of the male pollen? In answering this 
