FILICINEM. 



443 



mother-cell (Fig. 309, D). In Marsilia and Pilularia the antherozoids are pro- 

 duced in much the same manner; the protoplasmic contents of the microspore 

 divide into three cells : when the exospore bursts, the endospore protrudes containing 

 these three cells, of which one is sterile (rudimentary prothallium) and the other 

 two produce antherozoids: within each of these two cells divisions take place so 

 that a number of tetrahedrally-arranged primordial cells are formed which become 

 surrounded with thin cell-walls, and are the mother-cells of the antherozoids. As 

 in Ferns, we find also in Rhizocarps only a portion of the contents of the 

 mother-cell applied to the formation of the antherozoid. According to Millardet, 



Fig. 309. — Saliiinia natans ; A an entire microspo- 

 rangium, the tubes of the microspores st breaking through 

 (X about 100) ; B one of these tubes st protruding from the 

 envelope of the microsporangium h (x about 200), a the 

 antheridium still closed ; C tube with the empty anthe- 

 ridium ; D antherozoids (XSoo) (after Pringsheim). 



Fig. T,io.— Marsilia Salvatrix; A macrospore sp with its epispore st and the apical papilla projecting into its funnel: in 

 the papilla is a broad yellowish drop, sg the ruptured wall of the macrosporangiuni (X about 30). B a microspore burst after 

 the escape of the antherozoids ; ex the exospore, dl the protruding endospore containing granules, z, z the spiral anthero- 

 zoids, jyj' their vesicles containing starch-grains. The epispore of the microspore is no longer in existence (XSSo)- (The 

 exospore does not show the regular arrangement of the protuberances, which is indicated erroneously in the figure.) 



this portion assumes the form of a roundish turbid mass consisting of protoplasm 

 and starch-granules, which, during the formation of the antherozoids, becomes 

 gradually clearer, and, when the latter escape from the mother-cell, forms a 

 vesicle consisting of the unused protoplasm and the starch-granules lying in it. In 

 Pilularia, where the antherozoid is a thread coiled four or five times, this vesicle 

 remains attached to the mother-cell. In Marsilia, on the contrary, it adheres to 

 the posterior coils of the corkscrew-like antherozoid, which is coiled 12 or 13 times ; 

 and is often carried about with it for a considerable time by its swarming motion, 



