300 M. A. Brauu on the Nucleus of the Characese. 



grounds may indeed be found, but would lead far away from the 

 strict definition of the archegonium, as hitherto held. The sup- 

 posed asexuality of the lower Cryptogamia could not restrain the 

 indicated extension of the concc])tion of the archegonium to the 

 sporangial structures of the lower Cryptogamia, since a duplicity 

 of sexes is constantly being demonstrated as more widely extended 

 among the lower Ciyptogamia*, and the term antheridium has 

 also been frequently applied in analogous extension already (for 

 instance to the organs of the FucoidcEe, Floridea3, Lichens and 

 Fungi). The question is, therefore, whether the morphological 

 agreement of the female organ of fructification of the Characese 

 with that of the Mosses, Ferns, Equiseta, Lycopodiacca^ and 

 Ithizocarpese, is of a kind to render the use of the same name 

 for both suitable. 



It cannot be denied that it at first sight appears to have a 

 similar structure. The envelope — composed of five rows of cells- 

 terminating in the form of a five-pointed coronet, at a particular 

 period open — surrounding the central cell of the female organ of 

 fructification in the Characese, reminds us very much of the 

 more or less elongated style-like structure composed of a deter- 

 minate number of rows of cells, surrounding and surpassing the 

 central cell of the archegonia, especially when, as in Pilularia 

 and Equisetumf, the uppermost cells of these diverge like rays 

 in the same manner as the coronets of many species of Char a. 

 But when we turn back to the earlier stages of development, we 

 find that this resemblance is deceptive. The archegonium is in 

 all cases an originally closed, more or less elevated, cellular cover, 

 under which the central cell is concealed from the beginning. 

 The tubular canal leading to the central cell is formed subse- 

 quently by the separation of the cells from each other. The re- 

 verse takes place in the Characese ; here the central cell is ori- 

 ginally uncovered and gradually becomes overgrown and enclosed 

 by the cells of the envelope. Therefore the envelope and coronet 

 of the Characese are altogether different, morphologically, from 

 the envelope and tube which surround the central cell in true 

 archegonia, and this takes away all ground for close comparison ; 

 I shall not trace the more distant analogies which may exist be- 

 tween the archegonia of the higher Cryptogamia and the organs 

 of fructification of the rest of the Cryptogamia. A difi^rent ex- 



* See among others, Thuret, Recherch. sur les Antlieridies des Cryptog. 

 (Ann. des Sc. Nat. 3rd ser. xvi.) ; and Tulasne, Mem. p. servir a I'Hist. 

 des Lichens (Ann. des Sc. Nat. 3rd ser. xvii.). 



t See Hofmeister, Vergleich. Unters. der lioh. Cryptogamen, t. 21. {Pi- 

 lularia); Milde, Flora, 1852, No. 32. t. 7 ; and Hofmeister, Beitrage ziir 

 Kenntniss der Gefasscrypt. t. 17 & 18 {Equisetum). 



