HYBRIDISATION AND SYSTEMATIC ARRANGEMENT OF ORCHIDS. 219 
that failure in the fertilisation of two orchids must never be used as a 
proof that they are not nearly related. 
But if, on the contrary, one can obtain a hybrid between two genera 
of orchids, I hold the opinion that they are certainly nearly related. On 
this point I differ from Mr. Rolfe, who says, in his paper on “ Bigeneric 
Orchid Hybrids,” that species, and genera too, will always have to be dealt 
with in the scheme of classification according to their structural peculiari- 
ties and differences, without reference to the possibility of hybridisation 
taking place between them. 
Let us see how far hybridisation takes place between two genera 
which are not in the same subtribe. If we suppose that Bentham’s 
system is a natural one, we only know one apparent example, viz.: the 
hybridisation between Phaius and Calanthe. Bentham placed Phaius in 
his Bletiee, Calanthe in his Cawlogynee. But in my opinion Calanthe 
should have its place near Phaius in the Bletiea. 
There are some reputed hybrids which would certainly overthrow 
Bentham’s system and my own, too, if they really existed. Mr. Rolfe 
has spoken of hybrids between Zygopetalum and Lycaste, Odontoglossum 
and Zygopetalum, Chysis and Zygopetalum. But the plants had not 
flowered in 1888, when Mr. Rolfe wrote his paper; and if actual living 
hybrids have resulted from these crossings we should certainly have 
heard of them ere now. The result must, I think, have been the same as 
in a case described by Mr. Veitch, at whose establishment seedlings were 
obtained by crossing Zygopetalwm Mackai with several species of 
Odontoglosswm; but every one of these supposed hybrids proved after- 
wards to be Zygopetalum Mackau ; and it is quite improbable, nearly 
impossible to think, that in these experiments the pollen of Zygopetalum 
was not properly excluded. I believe, therefore, that the Odontoglossum 
pollen had sufficient influence to stimulate the Zygopetalwm into pro- 
ducing an embryo, but without impressing any of its own characters. 
For there was not the smallest character of Odontoglosswm visible in the 
seedlings raised—therefore they were not true hybrids. Again, some fey 
years ago the “ Gardeners’ Chronicle’’ reported that a hybrid between 
Phaius and Cymbidium was exhibited at one of the Society's meetings, 
but this supposed hybrid I consider to be a similar case to that of Zygo- 
petalum Mackau. For it is said that the plant looked in every respect 
like a strong-growing Phaius. Perhaps some one present saw this plant 
and can say if any signs were visible of the crossing with Cymbidium. 
It might be possible in this way to try some experiments in hybridisa- 
tion which would throw more light upon questions of systematic botany. 
For instance, I would call your attention to the genera Phaius and . 
Thuma. The flowers are so similar that Bentham considered Thunia 
to be only a section of Phaiws. On the other hand, Phaius has a lateral, 
Thunia a terminal inflorescence, and the habit is very different. If it were 
possible to obtain a hybrid between these two genera their close affinity 
would be proved. This experiment would be most interesting, because 
we do not yet know of any hybrid between an orchid with a terminal and 
one with a lateral inflorescence. 
It would also be of great interest to try the hybridisation of Zygo- 
petalum on one side and Promenea, Huntleya, Bollea, Warczewiczella, 
