308 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



species hitherto examined. As the later stages agree quite 

 closely in the two species, it is not likely that there are any 

 very marked differences in the early stages. Nevertheless, 

 it is much to be regretted that these early stages could not 

 have been compared, and it is to be hoped that these may 

 be examined soon in our American species. 



According to Hegelmaier (1874) tne embryo cell in S. 

 ramosum divides into three superimposed cells, but it is not 

 clear whether the second division is in the upper or lower 

 of the two primary cells. Before any longitudinal divisions 

 are formed there may be one or two more transverse divi- 

 sions, making thus a single row of four or five primary seg- 

 ments in the embryo. A very similar account is given by 

 Norner (1881) for the young embryo of several grasses, 

 except that he criticizes Hegelmaier's statement as to the 

 time of the fourth and fifth transverse walls, claiming that 

 these are probably not formed until after the first longitud- 

 inal divisions. He concludes that three is the regular 

 number of the primary segments in most Monocotyledons, 

 The more recent investigations in the embryo of the lower 

 Monocotyledons (Schaffner, 1896; Chamberlain, 1895; 

 Campbell, 1897, 1898, etc.) indicate that the basal cell, 

 where this becomes enlarged, does not divide further, and 

 that all the further transverse segmentation is in the terminal 

 cells, but it is probable that in Sparganium the segments 

 are the product of the division of the original basal cell. 



So far as could be judged from an examination of the 

 somewhat advanced embryo of S. simplex (figs. 37, 38, 39), 

 it looked as if the first longitudinal divisions in the terminal 

 segment occurred earlier than Hegelmaier gives for S. 

 ramosum, and it is doubtful whether here there are more 

 than three primary segments. A comparison of these stages 

 with Hegelmaier's figures 5 and 13 indicated that possibly 

 his segment 2 really belongs to the terminal segment. 



The basal segment never becomes enlarged as it does in 

 so many Monocotyledons, but remains usually very small 

 and generally divides early by longitudinal walls into three 

 or four cells, but sometimes a cross-section shows but two 



