XII LEPTOSPORANGIAT^ HETEROSPOREAL 403 



to the broad lower coils, the upper narrow ones being quite 

 free from them, and, according to Strasburger,^ probably of 

 cytoplasmic nature — unfortunately the development of the 

 spermatozoids in Marsilia 

 is especially difficult to 

 trace. The vesicle at- 

 tached to the broad lower 

 coils is very conspicuous 

 and contains numerous 

 starch granules as well 

 as albuminous ones. In 



Ptlulai'ia the long upper Fig. 209.— Ripe antheridium of Filularia glohdi/cra 



part of the SOermatOZOid ^'""^' *h°^''"» ''^^ '^^° vegetative prothallial cells 



_ y (.r, y), X375; B, free sperraatozoid, showing the 



is absent, and it apparently large vesicle (rO with the contained starch granules. 



corresponds only to the 



few broad basal coils of that of Marsilia, which are of nuclear 



origin, like the greater part of the body in the spermatozoid of 



Pilularia. 



The Macrospore and Female ProtJiallium 



The macrospores of the Marsiliacege are extremely complex 

 in structure, and are borne singly in the sporangia. In Marsilia 

 vestita they are ellipsoidal cells about .425 x. 750 mm. in 

 diameter, ivory-white in colour, and covered with a shiny 

 mucilaginous coating. The upper part of the spore has a 

 hemispherical protuberance covered with a brown membrane, 

 and it is the protoplasm within this papilla that forms the 

 prothallium. The apex of the papilla shows the three radiating 

 ridges like those in the microspores, and indicates that, like 

 those, the macrospore is of the radial or tetrahedral type. 



Sections of the ungerminated spore (Fig. 210, A) show a 

 structure much like that of the microspore, but more highly 

 developed. A noticeable difference is the segregation of the 

 protoplasm containing the nucleus, which occupies the apical 

 papilla. This is filled with fine granules, but is entirely free 

 from the very large starch grains of the large basal part of the 

 spore. The nucleus is somewhat flattened. A similar arrange- 

 ment of the spore contents is found in Pihilaria, but the apex 

 of the spore does not form a distinct papilla. The epispore is 

 of nearly equal thickness, except at the extreme apex, in 



^ Strasburger (11), vol. iv. p. 122. 



