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 

 varying 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 fullv developed embrvo. 



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