480 REPORT OF THE CONFERENCE ON GENETICS. 
groups haye terminal, others lateral inflorescences. The whole group of 
Monopodiales, whose stems grow many years at the apex, and have only 
lateral inflorescences, have also a distinct gland at the base of the pollinia. 
I think that this is the tribe which has reached the highest degree of 
evolution, and is the other end of the chain which begins with A postasiee. 
This monopodial type is not monophylitic. There are very few mono- 
podial orchids in America ; in the structure of their flowers the Hunt- 
leyine are very near the Zygopetaline, and may have been derived from 
them. The Dicheine approach the Oncidune; the genera Ornitho- 
cephalus and Lockhartia show a distinct tendency to monopodial growth. 
I think the former are an undeveloped stage of the latter ; also the strictly 
American Pachyphylle@ may have the same origin. 
The bulk of the Monopodiales, the Sarcanthine, are strictly geronto- 
geous; they may be a higher developed branch of the Cymbidiine which 
are also for the most part of Malayan origin. The genera Cyperorchis, 
Cymbidium, and Grammatophyllum show a distinct tendency to pass 
from the sympodial mode of growth to the monopodial one. 
A question which remains to be considered is, how the very small and 
imperfect embryos of orchids are developed from the normal embryo of 
monocotyledonous plants, and how the endosperm of the latter was lost. 
Generally speaking, we find very imperfect embryos in a seed 
without any nourishing tissue (1) in parasitical plants (Orobanche, 
Balanophoracee) ; (2), in saprophytic plants (Monotropa, Pyrola). 
The seeds of Ovobanche do not germinate if neither the seeds nor 
the roots of the plant on which the Orobanche feeds are present. So it 
becomes necessary for the latter to produce an enormous quantity of 
seed; and the seed itself is exceedingly small, in order that very many 
seeds may be produced with a restricted quantity of material. Large 
quantities of seed perish, without the possibility of ever reaching the host- 
plant. 
On the other hand, we know, from the researches of M. Noel Bernard, 
that the seeds of orchids may show the first signs of germination 
without symbiosis with a fungus, but that their further development 
depends upon the presence of this fungus (see p. 292 et seq.). Nearly 
the same difficulty arises as in Orobanche, and it becomes necessary 
that large quantities of very small seeds should be produced. 
In the case of the epiphytic orchids it is also probable that the 
dispersal of the seeds is effected in such a way that they reach the 
higher branches of trees where the orchid grows, and have sufficient light 
for prospering. We find here either adaptations for the dispersal by birds, 
as in epiphytic Avoidee and Bromeliacee, or these very small seeds, which 
are carried away by each current of air, as in orchids. Especially in 
these epiphytic orchids it is quite uncertain whether the seed will meet, on 
the branch of a tree, with the fungus which is necessary for the further 
development of the seedling, and the very numerous small light seeds 
are more profitable than the few heavy ones of Aroidee, Ke. 
One might even put the question, whether the reduction of the seeds 
to such an exceedingly small size in orchids did not happen because they 
originally grew as epiphytes, and whether the now existing terrestrial 
orchids have not been derived from epiphytic forms. But I think this 
