the development may be oriented in two directions: 1. 
(Pl. X, fig. 1A) all cells including the suspensor initial 
cell enter into the formation of the embryo, and the ma- 
ture embryo is suspensorless; 2. (Pl. X, fig. 1B) the sus- 
pensor initial cell appears as a distinct structure, either 
simple or modified. 
‘The suspensorless type of embryo is primitive and is 
to be found in Cypripedium of the Cypripedioideae and 
some members of the Neottioideae (Spiranthes, Listera, 
Neottia, ete.), while those with a suspensor are distrib- 
uted among the rest of the groups. Swamy, after having 
studied the embryogeny of a number of species, recog- 
nized five different types of suspensors (PI. X, fig. 2): 
Tyre I, with a single-celled suspensor, occurring in 
Cypripedioideae (Paphiopedilum) and also in the Neott- 
oideae (Vanilla, Epipactis, Goodyera, ete.); Tyrr II, 
which is unique in the family in developing a haustorium, 
is limited, so far as is known, to the Ophrydoideae. 
Tyres III to V are found in various representatives of 
the Kerosphaeroideae. 
There is a striking parallelism or correlation between 
the various types of suspensors and the relatively primi- 
tive or advanced stage of the main groups of the family. 
The mature embryo is an ovoid mass of cells without 
any definite differentiation of the tissues; thus, there is 
no endosperm in orchids. With respect to the method 
by which the undifferentiated mass of cells becomes or- 
ganized into the several organs of the embryo, no infor- 
mation is available as yet. Ina few instances, endosperm 
development has been reported, but in all of these this 
development is not consistent. Whenever it occurs, the 
tissue is of the nuclear type. This rare and casual occur- 
rence is noted in the Cypripedioideae and Neottioideae. 
Seeds. The mature embryo is enclosed in a loose, air- 
filled, reticulate testa which is characteristic of the Jcro- 
[ 68 | 
