THE VEGETABLE CELL. 121 



only the wall of the sac, at all events iii many species, is composed of two 

 layers of cells. 



The anthers of Chara, of wliicliFritzsclie (" Ueher den Pollen^'' G) lias given 

 the most accurate description, poshess a highly complicated structure. Into 

 the globular cavity enclosed by the eight cells containing red-colonred gra- 

 nnies, projects a flask-shaped cell, almost as far as the middle; from its 

 apex run out a mass of fine confervoid filaments, which are divided up 

 very closely into joints, and in each of the cells is developed a seminal 

 filament. The existence of an ii fusorial motion of these filaments was 

 observed by Bischoff (" Cryptog Geirr 1, 13) ; their exact form (plate 1, 

 ^g. 25, from Thuret), and the two cilise, by which they approximate closely 

 to seminal filaments of the Mosses, were first made out by Amici (whose 

 essay on this subject has not been printed) and Thuret (" Ann. d. Sc. nat. 

 2 /S'er." xiv., 66). 



In the Ferns the most different parts had long ago been interpreted, 

 without any judgment, as male organs, even the stomates of their leaves, 

 the annukis of their capsules, &c., when Nageli ('^ Zeitschr f. Wiss. Bot'' 

 1, 168) made the unexpected discovery that antheridia containing mov- 

 ing seminal filaments, occur upon their pro-embryo. This was contrary to 

 aU theory, yet as the observations of Thuret (" Ann, d. So. nat 3 /S'er.'* 

 xi. 5) and Leszcyc-Suminski shewed, nevertheless proved well founded. 

 The structure of fche antheridia of these plants bears a considerable re- 

 semblance to that in the Mosses ; they are composed of a pedicellated 

 cell, in the cavity of which is formed a second cell, fiUed with the small 

 cellules containing the spiral filaments. The entire organ bursts at its 

 summit, and extrudes its mucilaginous contents enclosing the seminal 

 filaments. The latter are ribbon-like and flattened down, possessing, 

 according to Suminski (plate 1, fig. 29) about six, according to Thuret 

 numerous cilise. Schacht (" Linncea,'' 1849, 758, (fee.) agrees with the last 

 statement, and states that the cilise are attached upon the narrow curves, 

 and not on the thick end at the widest curve of the filaments. 



Thuret found the same organ on the pro-embyi'o of the Equisetacese. 



The last Cryptogamia on which the spiral filaments have been found 

 are the Ehizocarpeae.* "N'igeli ('' ^eitschr f. Wiss. Botanik" iii. 199) suc- 

 ceeded in finding them in Pilularia. The pollen-grains (smal spores) 

 undergo a change after they have been discharged from the anthers, by 

 the inner coat bursting the outer, and afterwards tearing, itself, to emit 

 minute cellules which are filled with mucilage and starch. In these 

 minute cells a vacant space is subsequently formed at one end, in which 

 appears a spiral filament, turniag round and round, and leaving the cell 

 the thin end foremost. The same phenomena have been observed by 

 Mettenius in Iso'etes ("Beitr. z. Bo€' 1, 17). 



Thus have antheridia and sSminal filaments been found in all the leafy 

 Cryptogamia, with the exception of the Lycopodiacese.t Whether semi- 

 nal filaments occur in any other of the Thallophytes besides the Charas, 

 remains to be seen. It is true that Nageli (" D-ie neuer Algensysteme,^^ 1 d>6 ; 

 ''Zeitsckf. Wiss. BotJ' iii. 224 ; '' Bot Zeit:' 1849, 572) has stated that 

 antheridia occur in the Eloridese, the essential parts of which consist of 



* + Hofmeister {^^FrucMbildung^Keimungy Sc.,der Cryptogamen,^^ Ldpz., 

 1851) has since shewn that the small spores of Selaginella produce seminal 

 filaments, exactly in the same way as those of Isoctes. — A, H. 



