io6 
Briefe. 
both the pollen-masses dissolved into single pollen-grains, most of which have 
long tubes ; numerous tubes of cither pollen descend half way down the germen ; 
the poUen-mass of Epidendrum is to be reconnoitred only by the unaltered cau- 
dicula. Dec. 30 the germs of the two resting flowers (all the others having been 
dissected) are slightly curved to one side; this side, probably that of the Ep.- 
pollen swelling to a lesser degree than the other. 
I suspect that the sterility with the same plants pollen will be very common 
among Vandeae and one of the principal causes of them seeding so badly; for 
the several specimens of most of these plants grow scattered in the forests, at 
great distance from one another and thus the chance of pollinia being brought 
from a distinct plant is not very great. 
I already observed a second instance of this sterility, and of the mutual 
poisonous action of the same plants pollen and stigma. I found a large raceme 
of a Notylia with more than sixty aromatic flowers. The slit lending to the 
stigmatic Chamber is less narrow in this second species than in that mentioned 
in one of ray form er letters and a single pollen-mass might be introduced rather 
easily. I fertilized (Dec. 12^^ i;^^^ 14Ü1) almost all the flowers with pollen from 
the same raceme. Two days after fertilization the flowers withered and I found 
that the pollen-masses were dark brown and had not emitted a single tube. You 
see the poisonous action of own pollen is here much more rapid, than in Oncid. 
flexuosum. There remained eight flowers, which had not been fertilized, and these 
I fertilized (Decbr. ig^^ 20^^) with pollen-masses from a small raceme of a different 
plant of the species. Two of them I afterwards dissected and found the pollen fresh 
and having emitted numerous tubes. The other six have now fine swelling pods. 
Very different from the innocent pollen of Ep. Zebra, that of Notylia is as 
deletery to Oncidium flexuosum as are this latter plants own pollinia. Dec. 14 
I placed on the same stigma of Oncidium flexuosum one pollen-mass from a 
distinct plant of that species and one of Notylia. Decbr. 2 1 : the latter was brown 
as well as the neighbouring part of the stigma; the Oncidium pollen-mass was 
nearly fresh ; only on the side towards the Notylia-pollen a brownish st ripe began 
to make its appearance between pollen-mass and stigma. 
Strange as the destructive action of own pollen may appear, it may be 
easily shown to be of real use to the plant. If flowers are sterile with own 
pollen and if the introduction of own pollen-masses into the stigmatic Chamber 
prevents, as it does in Oncidium and Notylia the subsequent fertilization by other 
pollinia, it must be injurious to the plant to waste anything in the nutrition of 
flowers rendered useless by the introduction of own pollinia, and useful to become 
rid of them as soon as possible. This view is confirmed by a comparison of 
Oncidium and Notylia. Decbr. 21^^ I fertilized on a panicle of Oncidium flexu- 
osum 36 flowers (12 with own pollen, 24 with pollen from a distinct plant). 
Decbr. 24^'^ before any difference had appeared between the two kinds of pollen 
the peduncles and germs of 55 not fertüized flowers of this panicle were withering 
and discoloured yellowish, while all the fertilized flowers had green swelling 
germens. The panicle had about 160 flowers. 
In Notylia on the contrarj , when about of the flowers of a raceme were 
fertiHzed with own pollen, they all feil off in a few days without injuring even 
one of the not fertilized flowers. In Notylia fertilization is much easily effected 
