72 



HOFMEISTER, ON 



primary nucleus of this latter cell has become indistinct, in 

 fact hardly discernible ; it is manifestly undergoing dissolu- 

 tion (PI. VI, fig. 32). As soon as the canal which trans- 

 verses the neck of the archegonium is completely formed 

 by the dissolution of the transverse septa of the axile row 

 of cells, no trace of the primary nucleus of the central cell 

 is any longer perceptible. The free daughter-cell, the 

 germinal vesicle, now occupies about two third parts of the 

 central cell (PI. VI, fig. 33).* 



In those forms where the central cell of the archegonium 

 is smaller, the germinal vesicle at the time of the opening of 

 the apex of the archegonium, almost entirely fills the mother- 

 cell (PL VII, figs. 15, 16; PI. VIII, fig. 2; PL XII, fig. 1). 



Most archegonia are not developed beyond this stage. 

 The cell-walls, which adjoin the longitudinal canal of the 

 neck, assume a chestnut-brown colour, as also the inner wall 

 of the large central cell of the ventral portion. The spheri- 

 cal cell, which has originated in the latter, becomes trans- 

 formed into a dark brown mass. In individual archegonia, 

 however, seldom in more than one in the same inflorescence, 

 a fruit is produced by continuous division of the spherical 

 cell which has been formed within the central cell of the ven- 

 tral portion. It is more than probable that the action 

 upon the archegonium of the spermatozoa, emitted from 

 the antheridia of the same species, is necessary in order to 

 bring about the development of the rudiments of fruit. 

 Where antheridium-bearing plants are found in the 

 neighbourhood of those bearing archegonia, much fruit is 

 met with ; when the contrary is the case there is no fruit. 

 The common Lophocolea bidentata is a remarkable instance ; 

 this plant usually has abundance of archegonia, but very 

 seldom bears antheridia, and the fruit is proportionately 

 rare. 



Those species fructify the most abundantly which bear 



* The nucleus of the germinal vesicle very much resembles the defunct 

 primary nucleus of the central cell. This circumstance, and the rapidity with 

 which the above-mentioned process of development is gone through, led me on 

 a former occasion (' Vergleichende Untersuchungen,' pp. 37, 47,^67,) to look 

 upon the nucleus of the germinal vesicle as identical with that of the central 

 cell, and to assume that the formation of the germinal vesicle took place by 

 means of free cell-formation round the primary laicleus of the central cell. 



