STUDIES OF THE DEVELOPMENT OF PEPEROMIA HISPIDULA 38 1 
that all angiosperms are derived from archegoniates with a many- 
celled archesporium in the megasporangium. 
Finally it might be noted that though the causes producing these 
abnormal double sacs were not discovered it was found that the causes 
seem evidently confined to relatively few plants. Each of the abnor- 
mal plants may bear several of the double embryo sacs in the same 
spike, along with normal ones. The mature embryo sacs with two or 
three nuclei less than normal probably owe their peculiarity to some 
minor disturbance of nutrition which inhibits nuclear division before 
all of the megaspore nuclei of each sac have completed the second 
division. 
Theoretical Conclusions 
The peculiarities in the structure and development of the vegeta- 
and reproductive organs of P. hispidula recorded above l^ad to certain 
conclusions concerning the meaning and phylogenetic origin of these 
peculiarities. The most important secondary question which these 
facts may help to solve is that of the comparative primitiveness of 
this plant in relation to other members of its genus and family and to 
other angiosperms. 
We will consider the bearing of the facts here recorded under the 
following heads : (i) Vegetative structure. (2) Structure and develop- 
ment of the stamen flower and fruit. (3) Development of the arches- 
porium and megaspores (cell plates etc.). (4) Development of the 
embryo sac including division of megaspore nuclei, formation of the 
egg apparatus, endosperm nucleus and peripheral cells. (5) Develop- 
ment of embryo and endosperm. (6) Germination and food-storage 
in the perisperm. (7) Relative primitiveness of the 8-nucleate and 
i6-nucleate embryo sacs. 
I. Vegetative structure. — As was stated above, the structure of the 
vegetative organs of P. hispidula approaches in many features the 
simplest types known for these organs among dicotyledons. This is 
shown not only in the habit or organization of the plant as a whole but 
by the intimate structure of each of the individual organs. Thus the 
root is small, sparsely branched and has a single very simple vascular 
bundle. The stem likewise is relatively short and little-branched, is 
delicately herbaceous and has a simple internal structure, although the 
single, closed, vascular bundle is slightly more complex than that of the 
root. The leaf though furnished with trichomes, hydathodes and 
oil-cells on the surface has, aside from its three water glands, the simp- 
