June, 1905.] Embryo Sac and Embryo of Batrachium. 
357 
After fertilization the oospore begins to elongate and soon 
divides into a two celled embryo (Fig. 26). Before the first 
longitudinal division there is evidently another transverse one 
(Fig. 28). These two suspensor cells later divide in both directions 
varving considerably in method and order of divisions (Figs. .30 
and' 35.) The suspensor is short and does not seem to function 
long especially after the formation of the endosperm. The 
dermatogen is cut off by a series of periclinal walls from the 
octant and later divides by anticlinal walls. The cotyledons are 
small compared to the hypocotyl and the embryo is straight 
(Fig. 37). In the literature consulted there were but few of the 
Ranunculaceae in which the mature embryo was described. In 
Delphinium exaltatum Miss Dunn (15) finds a small heart shaped 
embryo with rudimentary suspensor and short hypocotyl. This 
seems to be the typical embryo in the Ranunculaceae. 
The definitive nucleus divides immediately after fertilization 
and when the four celled embryo was found there was a single 
layer of endosperm completely lining the embryo sac (Fig. 29). 
These nuclei were not enclosed in cell walls but showed faint 
radiations (Fig. 31). In later divisions however, walls are formed 
and the entire embryo sac is filled with endosperm cells of varying 
shapes and sizes. Those in the antipodal region are large and 
rounded, those near the embryo wedge shaped or rhomboidal, 
and the peripheral layer is flattened. (Fig. 32.) The cells store 
up an abundance of starch (Fig. 34) which nourishes the young 
embryo. The cells are arranged in a radiate manner and as the 
young embryo enlarges the surrounding cells are emptied of their 
store (Fig. 33). 
The inner wall of the carpel is made up of a layer of elongated 
cells which are longest in the plane at right angles to the axis of 
the carpel. Next to these cells there are four or five layers 
elongated at right angles to the first and rather crescentic (Fig. 
38). As the ovule matures these cells develop thick perforate 
walls while the cells beneath the epidermal layer become some- 
what separated to form a delicate spongy tissue (Fig. 39). These 
cells seem to contain some starch. The thickened cells make it 
a difficult matter to section the mature ovule so as to obtain good 
sections of the fully developed embrvo. 
