232 THE ORCHID REVIEW. [AuGuST, 1922. 
important than structural adaptations for flight. Together with the spores 
of ferns and other cryptogams, very light seeds are easily transported by 
the ordinary tropical monsoon. In winds which reach a velocity of ninety- 
eight feet a second, special apparatus is unnecessary for transport of seeds 
of excessive lightness. In the Indo-Malayan region, winds that reach this" 
velocity are not infrequent during storms. The extreme reduction in weight 
that has rendered Orchid seed easily conveyable even by light winds is 
well exampled by Dendrobium attenuatum, whose seeds weigh only 
0.0000065 gr. 
To account for the appearance of Orchids on Krakatau, where it is 
scarcely probable that mycorrhizal fungi were present that could enter into 
symbiosis with them, one should bear in mind that slow germination is a 
striking characteristic of Orchid seeds. The seeds, when dehiscence of the, 
ripe capsule takes place, may fall among the roots of the parent plant and 
in time become inoculated. If after this any of the inoculated seeds 
become dislodged by violent storms, it is conceivable that in the early 
stages of germination, even with their fungal freight, they might easily 
withstand a journey of from twenty to thirty miles without undergoing 
lethal desiccation. As evidence that such a supposition is not illogical, I 
offer my own experience with germinating seeds of Goodyera pubescens 
R. Br., transferred from colonies to my laboratory. Although these 
germinating seeds in detachment from the humus lost the characteristic 
and extremely delicate rhizoids of the protocorm stage of development (that 
is, the hair-like structures through which the fungal hyphe retain 
connection with the humus), they quickly developed new ones, and in a 
petri dish placed under a bell jar on the laboratory window-sill they made 
substantial growth. 
It is probable, then, that slow germination is an advantageous charac- 
teristic. It may be connected in some way with the adaptation of the 
species for dispersal by wind after germination has begun. This assumption 
is perhaps necessary, because the mycorrhizal fungus is not known to occur 
as an autonomous organism comparable to an omnipresent mold. It does 
not occur as a widely distributed fungus which simply lies in wait for the 
haphazard advent of wind-borne Orchid seeds with which it immediately 
initiates a symbiotic union. If Orchid seeds germinated quickly and gained 
weight rapidly ; if the embryo immediately put forth roots and in a brief 
time secured a firm hold on the substratum, the likelihood of dispersal after 
the entrance of the mycorrhizal fungus would be diminished and oppor- 
tunities for successful dispersal severely limited. Even after the fungus has 
entered the embryo, the seed is but a trifle heavier than it was at the time of 
dehiscence of the capsule in which it ripened. Adaptation of the seeds for 
purposeless flight would be a sad adaptation indeed. 
