The Morphology of Ruppia Maritima. 131 
point, however, the gross morphological development will be fol- 
lowed duriny the history of micro- and megasporangia and male 
and female gametophytes. 
Very early the floral rudiment can be distinguished from the 
vegetative cone by its greater lateral development, giving it a com- 
parative thickness, and because even here the two protuberances, 
each of which is to develop into a flower, are already apparent 
(Pl. IX, fig. 52). In Pl. IX, fig. 53 these two floral primordia have 
become more distinct. Pl. IX, fig. 54 shows a more advanced stage 
with the floral primordia acquiring the flattened disk form which 
characterizes them at this period, and the floral scale leaf which, 
as has been shown, corresponds to the spathe just appearing. In 
Pl. IX, fig. 55 all of these parts are still more developed, and in 
Pl. IX, fig. 56 one first sees evidence of a segmentation of the 
several parts of the flower. At this point each flower is still disk- 
shaped with the thecae of the young stamens—or their primordia 
—as four swellings situated diametrically opposite one another—the 
central part of the disk being elevated and representing the region 
of the future pistils. The rhachis also first appears well developed 
here, at least at its base. 
Three points of interest will be noted in this early floral devel- 
opment : — 
1. The ongin of the flowers is lateral, forming a type of in- 
florescence which is not uncommon, and explained on the hypoth- 
esis that the nourishment of the vegetative cone is appropriated 
by the lateral members (Goebel, 1898, pp. 178, 179). 
2. Both flowers in the spadix are of the same age. Their origin 
in the periblem takes place almost simultaneously, and they remain 
contemporaneous throughout their entire development. This occurs 
also in Potamogeton, according to Hegelmaier (1870). 
3. The development of the anthers precedes that of the pistils. 
Subsequently, the pistils appear as four rounded prominences. 
These develop by degrees, (but always much behind the staminal 
development) into the mature, rather cylindrical ovaries surmounted 
by sessile, peltate stigmas (Pl. X, figs. 58-66). 
MicROSPORANGIUM 
The initial cells of the archesporium are first clearly recognizable 
at such a stage in the floral development as is represented in PI. XI, 
fig. 68, where the length of a single young flower in section is 
