1913] YORK—DEN DROPHTHORA 93 
During May and June of 1910, observations were made on 18 
different species belonging to 8 different genera of Loranthaceae 
occurring in Jamaica, and material was collected for a detailed study 
of their development. From a part of this material the following 
study was made. This paper, which embodies the results of the 
beginning of a comparative study of the morphology and physi- 
ology of the North American Loranthaceae, embraces an account 
of the origin and development of the embryo sac and embryo of 
Dendrophthora opuntioides and D. gracile, together with a discussion 
of the physiological relation existing between the gametophyte 
and sporophyte of these plants. Although this study may lead 
to the extension of our knowledge of the life histories and relation- 
ships of certain genera of the Loranthaceae, and perhaps to a clearer 
understanding of the systematic position of this family, one of the 
most interesting as well as most difficult problems for solution will 
be the determination of the factors which have caused the striking 
modification and adaptations in the reproductive organs. The 
material on which this study was made was killed in medium 
chromacetic acid and cut in sections 10 # in thickness. 
To Professor Duncan S. JoHNsoN the writer wishes to express 
his sincere thanks and appreciation for helpful criticism and 
advice. 
Dendrophthora opuntioides 
Dendrophthora opuntioides (L.) Eich. receives its name from its 
Opuntia-like appearance (text fig. 1). It is a bright yellowish green, 
glabrous shrub, seldom more than 4dm. in height. The stems 
are jointed, constricted at the nodes, and all the joints of a branch 
are strongly flattened in one plane. The secondary branches 
arise in this plane in the axils of the reduced scalelike leaves at the 
nodes. The internodes are usually paddle-shaped, tapering toward 
the base. The flowers are opposite, isolaterally arranged in spikes 
which arise from the nodes of the younger portions of the stem in 
the same manner as the vegetative branches. The spikes thus 
formed are strongly flattened structures, whose plane of flattening 
is parallel with that of the stems. The position of a branch as 
it develops may vary somewhat from the plane in which the stems 
are flattened, so that all parts of the whole plant do not always lie 
