THE HIGHER CRYPTOGAMIA. 19 



facts observed in all essential points ; but there is a dif- 

 ference of opinion as to the interpretation of these facts. 

 Mohl assumes that the duplication of the secondary nuclei 

 takes place by gradual constriction ;* Nageli, that it occurs 

 by the growth of a septum bisecting the internal cavity of 

 the secondary nucleus of the first order, and by the subse- 

 quent differentiation of the two halves ; Schacht's notion 

 of the process approximates to that of Mohl, from which my 

 own explanation only differs in the mode of expression. 



Figures of Anthoceros are to be found in Dillenius 

 (' Historia Muscorum/ torn, lxviii, figs. 1, 2), in Schmidel 

 ('Icones pi.,' t. xix, A. lavis ; t. xlvii, A. punctatus), and 

 also in Heclwig {A. Itevis, theoria generat., ed. ii, t. xxix, 

 xxx). According to these figures, the characters of the 

 flowers appear to be principally grounded upon a " radi- 

 ating mode of growth, progressing in all directions from a 

 central point of attachment." The history of the develop- 

 ment of the fruit which is given by the above observers 

 does not extend further back than the appearance of the 

 fruit above the edge of its veil or covering. Nees v. Esen- 

 beck (' Naturgeschichte der Europ. Lebcrmoose,' B. iv, 

 s. 334, 1838) describes the rudiments of the fruit, whilst 

 enclosed in the substance of the stem, as archegonia {Stem- 

 pel). Bischoff, on the other hand, had already (1835) 

 rightly described the relation of the young fruit to the 

 tissue of the stem which covers and encloses it (' Nova 

 Acta Acad. C. Carol. Leop.', T. xvii, p. 2, s. 934), and has 

 figured it, (' Hanclb. der Botan. Terminol/ B. ii, t. lxvi, 

 fig. 2783.) He does not mention the archegonia. Schacht 

 has lately (' Berliner Bot. Zeit. Jahrg,' viii, 1850, N. 24 

 26) published a contribution to the history of the develop- 

 ment of the fruit and spore of Anthoceros. My own obser- 

 vations, in the 'Vergleichende Untersuchungen,' were com- 

 pleted before the appearance of Schacht's paper. Schacht has 

 only once observed an archegonium (1. c. 459), unfortunately 

 an imperfect one, of which the essential parts were already 

 decayed. The arrangement of the cells of the stem adjoining 

 the base of the archegonium appeared to him to bear a great 



* See Wagner's ' Handwoiterbuch der Physiologie,' 13d. iv, s. 215. 



