The Morphology of Riippia Maritima. 139 



however. If they were, it is evident that a tetrad similar to that 

 in Ruppia would have resulted. The upper daughter-cell with its 

 two nuclei now becomes disorganized, and the lower cell becomes 

 the embryo-sac, its nuclei producing directly the embryo-sac nuclei. 



Zostera marina forms three megaspores, according to Rosenberg 

 (1901, I, p. 9), the lowest functioning. The uppermost, however, in 

 his Figure II looks much like Figure 51 of Murbeck (1902), and 

 like many of m}- own preparations, gives indications of two cells 

 obliquely arranged. 



In Zannichellia the state of affairs is surprisingly different. Ac- 

 cording to Campbell (1897, pp. 45, 46), a row of three cells is 

 formed, of which the uppermost becomes the functioning megaspore. 

 Since this is so strikingly diverse from what takes place in Ruppia, 

 Zostera and Potamogeton, it would seem as if it needed confirmation. 



The functional megaspore now proceeds to the formation of the 

 embryo-sac by a series of stages which are quite in line with 

 those which have been found to be so remarkably constant among 

 the Angiosperms. PL XII, fig. 82 shows the megaspore nucleus 

 in process of division, while Fig. 83 discloses the resulting two 

 nuclei, one at each end. Fig. 84 shows the four nuclei coming 

 from these two. Fig. 85 represents a mature embryo-sac with 

 S3'nergidae and o,^^ of characteristic form and structure. The 

 antipodal cells are always three in number, their nuclei being sur- 

 rounded by a definite layer of cytoplasm and apparently by a thin, 

 membranous wall. Often they appear rounded in form (PL XII, 

 tig. 85) and again angular (Fig. 86), in the latter case showing 

 clearly their relations to each other. They resemble strongly those 

 figured by Murbeck (1902, fig. 53) in Ruppia rostellata and by 

 Campbell (1897, fig. 109) in Zannichellia palustris, and like them 

 are situated in a small pouch at the base of the embryo-sac. 



A peculiarity of these antipodals is the conspicuous blue color 

 of their nuclei with the triple stain, showing an unusual tint of the 

 blue, and possibly indicating degeneration. Thus they are strongly 

 contrasted with adjacent nucellar nuclei and may be readily dis- 

 tinguished. They were not observed to divide, however, as in the 

 case of certain recently investigated monocotyledons. Apparently 

 their life is short, for they disappear in stages slightly older than 

 PL XII, fig. 85. 



i- Male Gametophtte 



*• Since my studies of the male gametophyte of Ruppia maritima 



agree closely with those of Murbeck (1902), it would be useless here 



Trans. Conn. Acad., Vol. XIV. 10 December, 1908. 



