204 Rhodora [Jury 
HABENARIA TRIDENTATA. In diembryonic seeds, which are not 
uncommon, the embryos lie side by side (Fig. 6), have separate 
suspensors (s), and are similarly oriented. 
HABENARIA BLEPHARIGLOTTIS. When two embryos are present 
(Fig. 5), they are plainly to be seen, as one lies ordinarily a little 
above the other and both embryos keep their roundness well. The 
proportion of twin-seeds is small. 
This species shows a somewhat striking elaboration of the 
suspensor, which comprises at least six or seven cells (Fig. 10). 
Nearly all the cells emit processes, some short and fingerlike and 
reaching out laterally to the seed-coats or placenta, others filamentous 
and running parallel with the body of the suspensor into the tissue 
at the base of the seed-stalk. All these prolongations are filled 
with dense protoplasm. The processes of the terminal cells are 
insinuated between the cells of the placenta. The whole apparatus 
seems to be a well-devised instrument of nutrition. | 
The embryo lies at the centre of the field which every now and 
then we hear characterized as peculiarly exempt from modifying 
influences. Features of the reproductive system, so it has been said, 
are relatively constant from group to group in any evolutionary 
series, as compared with characters of the vegetative system. Yet 
as a matter of fact the moulding forces reach even the embryo rather 
directly in many cases. Thus in the family under discussion the 
adaptive tendencies in the matter of seed-dispersal have worked first 
to reduce the size and specific gravity of the seed as a whole. The 
mature seed has but one coat and that isair-filled. Both perisperm 
(nucellus) and endosperm have been done away with. The germ 
itself has lost distinction of stem and leaf. Finally, in the absence 
of the usual means of feeding the growing embryo, complicated 
sucking-organs (suspensors) have often been developed; and the 
diversity which obtains within the limits of this one family in this 
respect is remarkable. In some tropical species, as for instance 
Phalaenopsis grandiflora (Fig. 9), the cells of the “suspensor” 
grow out in tubular fashion not only toward the exostome, but 
also in the opposite direction, so that the embryo proper is envel- 
oped by the filaments. 
With regard to twin-embryos, it should be noted that we now have 
them in both diandrous and monandrous divisions and in all the 
