220 REPORT OF THE CONFERENCE ON GENETICS. 
Pescatoria, on the other. Bentham includes all these plants under the 
generic name of Zygopetalum, but the variations of the leaves and the 
habit are very different. At present we know of no hybrid between an 
orchid with convolute leaves and one with conduplicate leaves, save only the 
reputed Phaio-Cymbidiwm, which would surely be an intermediate form, 
if it is really a hybrid. 
Again, the genus Trichosma has much similarity to Hria, as regards 
the flowers ; but in the morphological structure of the whole plant it is 
nearer Thunia. It has also been united with the genus Celogyne. A 
trial should be made to see whether Tvrichosma gives hybrids with Hria, 
Celogyne, or Thunia. 
Bentham founded a special subtribe, Notyliee, for the genera which 
have a gland at the base of the pollinia and a dorsal anther. This sub- 
tribe contains the genera Cirrhea, Macradenia, Notylia, Acriopsis, 
Telipogon, Trichoceros, Podochilus, Appendicula. This group is an 
entirely artificial one: thus Cirrhea is quite near to Gongora, Notylia 
to Oncidiwm, Macradenia to Bulbophyllum. If anyone succeeds in 
obtaining a hybrid between Cirrhea and Gongora, or Notylia and 
Oncidium, it would be a strong argument for my opinion. 
Octomeria is somewhat intermediate between the subtribes Plewro- 
thallee and Leliee. Someone should try to cross it with Plewrothallis or 
Stelis on the one side, and with Hartwegia or Arpophyllwm on the other. 
The beautiful genus Sobralia is placed by Bentham in his subtribe 
Vanillee, because the pollinia are soft and granular. I consider that 
Sobralia is more nearly related to the Lelie, to Cattleya, and to Lelia 
itself. It would be very interesting if anyone would try to cross Sobralia 
with Vanilla, the next genus in Bentham’s arrangement, and on the other 
side with Cattleya. 
In conclusion, it may perhaps be useful to mention what differences 
have hitherto proved no obstacle in obtaining hybrids between different 
genera of orchids and what have so proved. The following differences 
present no obstacle to hybridisation :— 
1. Absence or presence of a gland at the base of the pollinia 
(Phaio-Calanthe). 
2. The number of the pollinia (L@lio-Cattleya, Epi-Lelia, Lepto- 
Lelia, Zygo-Colax). 
5. A long or very short column (Sophro-Lelia). 
4. A twisted or very twisted column (Anewctonaria). 
5. A concave or flat stigma, or, on the other side, well-developed 
stigmatic processes (Sophro-Lelia). 
6. An adnate or free lip (Hpi-Cattleya, Epi-Lelia, Odontioda). 
The following differences must, until further proof, be considered to 
be impediments to hybridisation :— 
1. Monopodial or sympodial structure of the whole plant. 
2. Lateral or terminal inflorescence. 
3. Convolute or conduplicate variations of the leaves. 
In the orchids we generally find that great differences in the structure 
of the flowers and the pollinia are easily overcome in hybridisation, but 
