450 Mottier . — The Embryology of some Anomalous Dicotyledons . 
very skilful manner an immense mass of facts, derived from a thorough study 
of the anatomy of a large number of seedlings, chiefly of the Liliaceae. As 
will be more explicitly indicated in a later paragraph, this observer regards 
the Angiosperms as monophyletic in origin, the Dicotyledons being the 
more primitive, from which the Monocotyledons have been derived. 
Observations. 
The writer’s observations were made upon Actea alba (L.), Mill., 
Delphinium tricorne , Michx., Aquilegia canadensis , L., Syndesmon (Anemo- 
nella) thalictroides (L.), Hoffmg., of the Ranunculaceae, and Sanguinaria 
canadensis , L., and Stylophorum diphyllum , Michx., of the Papaveraceae. 
In all of these species the development of the embryo was carefully traced 
from a very young stage to that found in the ripe seed. Although all 
show certain well-marked anomalies in the origin of the cotyledons, yet it 
will be seen from what follows that a gradual transition from a clearly 
anomalous type to that which is typically dicotyledonous is to be found in 
the same family, and even in the same species of a genus. Owing to the 
fact that the anomalous character is more pronounced in certain individuals 
of Actea alba , a detailed account of the embryo in this species will be 
given first. 
Actea alba. 
No effort was made to find the earlier cell-divisions in the young 
embryo, as that part of the process was not considered important in this 
study. The youngest embryos observed in Actea are represented in Plate 
XXVI, Figs. 1 and 2. At this stage it is clear that the embryo consists of 
a short suspensor about two cells broad and a somewhat club-shaped or 
cylindrical body, as indicated in both longitudinal and transverse sections 
(Figs. 1, 2, and 3). The cells of the suspensor are characterized by the 
presence of starch in greater or less abundance, while those of the rest of 
the embryo contain little or no starch. Whether Fig. 2 is an older stage 
than Fig. 1, or merely a section at right angles to the plane of Fig. 1, was 
not determined. Fig. 3 is a cross-section through the middle of an embryo 
of the stage shown in Fig. 1. The superficial cells now undergo periclinal 
and anticlinal divisions, whereby the epidermis is differentiated, while the 
cells within divide in three planes (Fig. 4). With further growth the 
embryo becomes symmetrically pear-shaped (Fig. 5). The distal end 
is either nicely rounded as in the figure just mentioned, or it may be 
somewhat flattened. The suspensor has grown only a little. Its cells 
contain starch, although this substance is seen in a few neighbouring cells 
of the remaining embryo. 
At this stage begins the development of the cotyledonary primordium. 
As the true and exact nature of this can be better ascertained in series of 
