The Morphology of Ruppia Maritinia. 131 



point, however, the gross morphological development will be fol- 

 lowed during 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 origin 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 

 b}^ sessile, peltate stigmas (PL X, figs. 58—66). 



MiCROSPOEANGIUM 



The initial cells of the archesporium are first clearly recognizable 

 at such a stage in the floral development as is represented in PL XI, 

 fig. 68, where the length of a single 3^oung flower in section is 



