ON THE HOMOLOGIES OF THE SUSPENSOR. 65 



foot takes origin, and from one of the upper quadrants the stem 

 is developed. Sadebeck,i in a recent paper, has given an account 

 of some observations upon the embryology of Equisetum. Unfor- 

 tunately I am only able to become acquainted with them by 

 means of a short abstract. It appears from this that the most 

 superficial segment [i.e. the anterior superior) developes into the 

 stem, the most deeply placed into the root, and that the two 

 lateral segments together form the first leaf-sheath, no foot being 

 developed. 



The development of the embryo of the Mosses^ begins with a 

 division of the oosphere in a plane, which is nearly or quite at 

 right angles to the axis of the archegonium, and of the two cells 

 tiius formed the superficial forms the sporogonium, the deeply 

 placed, the seta and foot. According to Kienitz-Gerloff,^ how- 

 ever, the sporogonium of the true Mosses is formed, not from 

 the whole of the upper segment of the oosphere, but from a 

 portion only of it, the remainder of the segment remaining 

 undeveloped. Leitgeb^ had already noticed in Anthoceros that 

 one half of the upper segment became more developed than the 

 other, a condition which may have become more fully expressed 

 in Mosses. 



The first division of the oosphere of the Hepaticse (fig. 7) 

 takes place in a plane, which in the lower forms intersects the 

 axis of the archegonium at an acute angle, but in the Junger- 

 manniese at right angles. The more superficial of these two 

 cells — the one, that is, which more immediately underlies the 

 neck of the archegonium — undergoes numerous divisions, by 

 means of which the tissue of the future sporogonium is formed. 

 The tissue resulting from the frequent division of the more 

 deeply placed cell forms, according to Kienitz-Gerloff,^ the seta, 

 the lower expanded portion of which is termed the foot. The 

 only exception to this mode of development is to be found 

 in Eiccia, the oosphere of which simply gives rise to a sporogo- 

 nium. 



It appears, then, that with this solitary exception, the first 



1 Read at Hamburg, Sept. 26, 1876. 



2 Tlie embryology of mosses is treated of in the following works : — 

 Hofnieister, ' On the Higlier Cryptogamia,' Ray Society, 1862. Schimper, 

 ' Rech. ariat. et physiol. sur les Mousses,' 1848. KiJhn, ' Entwick. d. 

 AiidreEeaceen,' But. Mittheil., v. Schenk und Luerssen, Bd. i, 1874'. Vouk, 

 " Eutwiok. d. Sporogouiums von Orthotrichum," Sitzber. d. Wien. Akad., 

 1876. 



3 ' Sitzber. d. Gesell. Naturf. Ereunde zu Berlin.' Marz, 1876. 

 * 'Unters. ueb. Lebermoose,' Heft, ii, 1875. 



5 "Vergl. Unters. ueb. Entwick. d. Lebermoos-sporogoniums," Bot. 

 Zeiig., 1874-75, see also Leitgeb, "Entwick. d. Kapsel. v, Anthoceros," 

 Sitzcr. d. Wien. Akad., 1876. 



VOL. XVIII. NEW SER. E 



