176 HOFMEISTER, ON 



threads. The same was the case with Ftmaria hygrometrica. 

 The production of leafy plants out of pro-embryonal threads 

 was considered by Hedwig's followers to arise from the 

 amalgamation of several threads of the pro-embryo, so as 

 to form the leafy stem (see Schleiden, ' Grnndzuge,' 

 2nd edit., vol. h\, p. 60), an error which was grounded 

 upon the fact that numerous cells of the base of the 

 young leafy plant usually grow into new pro-embryonal 

 threads, the Brtitkeinifaden of Nageli. Nageli clearly 

 explained the development of the leafy axis out of the 

 pro-embryo. He showed* that at the commencement 

 of the formation of the moss -stem, the terminal cells of 

 individual branches, or of the principal axis of the spores 

 or brood-germ-threads, expand, and, through division by 

 means of septa inclined in different directions, become con- 

 verted into a cellular body, which afterwards produces 

 leaves, and thus indicates the rudiment of a stem. The 

 results obtained by Nageli have been extended by P. W. 

 Schimper (' Rech. sur les Mousses,' Strassburg, 1848, 

 ss. 1 4) to such a number of different species, that there 

 is no doubt of their general application. 



The spermatozoa of the mosses, and (with the exception of 

 an imperfect observation of Bischoff's,) of the cryptogamia 

 generally, were discovered by Unger in 1834 ('Mora,' 

 1834, p. 145 ; more fully in ' N. A. A. C.,' xviii, pp. 2, 

 690, 790). Unger describes the spermatozoa as con- 

 sisting of a thick body, and a thin thread-like prolonga- 

 tion, which goes in advance when the body is in motion, 

 and is of a spiral form.f The motion of the spermatozoa 



* ' Zeitschrift f. wiss. Bot.,' 2, 168. 



f ' Bischoff, Kryptog. Gewachse ' (Nurnberg, 182S), p. 13 note, mentions 

 that lie has always noticed in freshly-opened globules (antheridia) of Chara 

 hisjnda, a medley of numberless infusoria. They appeared to consist of small 

 dark points, which were connected by transverse lines like little strings. They 

 exhibited a continuous tremulous motion, by means of which the individual 

 points, with their stems, revolved round one another. Bischoff was doubtful 

 whether these "infusoria" originated from cellular threads in the interior of the 

 antheridia. It is hardly necessary to remark that Bischoff's dark points are 

 only the optical sections of the turning points of the spiral spermatozoon. 

 Schmidel's observations on Fossombromia (Ic. pi., p. 85) and those of Nees v. 

 Eseubeck ('Flora,' 1822, p. 34) on Sphagnum afford still less claim to the dis- 

 covery of the Spermatozoa, inasmuch as both observers only saw the motion o. 

 the escaped contents of ruptured antheridia, but did not distinguish the forms 

 of the motile bodies. 



