The Morphology of Ruppia Maritima. 147 



cell nucleus, with the majorit}' of the cytoplasm, occupies a pos- 

 ition at the base of the cell, the upper part containing one or 

 more large vacuoles. This appearance, although not invariable (cf. 

 fig. lOlj, seems a quite general one in the disposition of the cell- 

 contents at all stages except the ver}- earliest. The same has been 

 noted in Zostera (Rosenberg, 1901, I, pp. 11, 12) and Potamogeton 

 (Wiegand, 1900, p. 37). 



Although the suspensor-cell is now (PL XIII, tig. 100) enormous 

 in size, this is in fact only a stage in its enlargement. Fig. 101 

 testifies to what proportions it eventually attains. At the same time 

 its nucleus attains a large size. In somewhat later stages the sus- 

 pensor-ceU commences a gradual disintegration, until, at a period 

 of embryo development, such as in fig. 106, the outlines of the ceU 

 can be no longer distinguished, although its nucleus is still apparent 

 in a condition of disorganization. 



During its development, the suspensor-cell is in contact with the 

 micropylar end of the embryo-sac for some time, but may eventually 

 become free, as Wiegand (1900, pp. 37, 38; has also noted in 

 Potamogeton. 



In connection with this remarkable growth, the statements of Rosen- 

 berg (1901, I, p. 12), who describes a similar suspensor in Zostera, 

 may be quoted. In writing of the nucleus of this cell he says: "Der 

 Kern des EmlDryotragers .... macht eher den Eindruck, als ob in 

 demselben eine rege Stoffbildung vor sich ginge ; etwa eine Auf- 

 nahme von Stoffen, die in dem Kern weiter umgebildet werden, 

 um spater in das Embryo zu gelangen." It might be added that 

 not only the nucleus, but also the whole cell, judging from its ap- 

 pearance and time and manner of development, has obviously the 

 function of reception and preparation of nourishment for the embryo. 

 It is significant also to note that at the time of the degeneration 

 of this large suspensor-cell, the endosperm nuclei are relatively 

 abundant. 



Although a similar large basal cell occurs in Naias (Campbell, 1897, 

 p. 26), ZannicheUia (Campbell, 1897, pp. 27, 48), Zostera (Rosen- 

 berg, 1901, I, pp. 11, 12) and Potamogeton ('Wiegand, 1900, p. 87j, 

 only in Zostera does it represent the entire suspensor as in Ruppia. 

 In the remaining genera other small secondary suspensor-cells are 

 formed above the large basal cell. 



It will be seen that the three-celled stage of the proembryo 

 (PL XIII, fig. 98) is essentially similar to that of Sagittaria (Schaffner. 

 1897, II, p. 262 and PL XXIV figures 46, 47) and Ahsma (Schaffner, 

 1896, pp. 129, 130), which has been regarded as typical of the 



