164 BOTANICAL GAZETTE [FEBRUARY 
type of embryo sac, as a basis of comparison with the other species to be 
described later. His topics are as follows: habit and vegetative structure, 
development of the spike and flower; the stamen, microspore, and pollen tube; 
the carpel and fruit, ovule and seed; = gas sac, embryo, and PE, 
germination; and abnormal embryo s 
It is a very full and satisfactory aie i of the facts, on the basis of 
which the following conclusions are reached. In vegetative structure, P. 
hispidula is simpler than any of its salalive: and its delicate herbaceous stem, 
as well as the accompanying structures, are probably due to recent modifica- 
tion of the more complex type of structure. The flowers are naked, and there 
is no evidence that they ever possessed a perianth. The megaspore mother 
cell develops a tetrahedral tetrad of megaspores, whose delicate walls soon 
disappear, leaving the 4 nuclei in a continuous protoplast. The 4 megaspore 
nuclei divide to form the characteristic 16-nucleate embryo sac, with its egg 
and solitary synergid, and its huge endosperm nucleus, formed by the fusion 
of 14 nuclei. This embryo sac cannot be regarded as primitive, but rather as 
a compound sac, a structure unknown among the simpler forms. The restric- 
tion of the function of the endosperm to that of a ‘“‘nurse”’ for the embryo, the 
food supply being stored in the perisperm, is regarded as “‘the next to the last 
step in the disappearance of the endosperm,”’ which becomes practically com- 
plete in the Helobiales, Orchidaceae, etc. 
To the reviewer, this study is a most satisfactory illustration of the fact 
that many conditions which appear primitive upon superficial examination 
may prove upon real examination to be derived and specialized conditions. 
Peridium formation in the aecium. —Kurssanow™ adds several interest- 
cells are normally produced in these peripheral chains as well as in the interior 
aeciospore chains. They are not intercalary in position, but are cut off at the 
lower outer corner of the initial cell when this cell is about the third from the 
base of the chain. They enlarge somewhat after their abstriction, but soon 
outer wall of the peridium and the sterile tissue that surrounds it. The pro- 
duction of intercalary cells was more readily followed and the cells were more 
persistent in the deep-seated, cylindrical aecia of Puccinia graminis and Gym- 
nosporangium tremelloides than in any of the other 8 species with cupulate 
2 Kurssanow, L., Uber die shyisemenemtlane fe im Aecidium. Ber. Deutsch. 
Bot. Gesells. 32: ee pl. 6. figs. 2. 1914. 
