276 MR. J. R. VAIZEY ON THE ANATOMY AND 
“Leptosporangiata”*. The parenchymatous sheath may be called 
the endodermis, as Prof. Haberlandt calls it by the German 
equivalent Schutzscheide. 
The term Leptoxylem will then be used to designate the water- 
conducting tissue only of the sporophyte of the Muscinew; and 
Leptophloém to designate the tissue only of the sporophyte of 
the Muscinez which has the same function as the bast in the 
Vasculares. 
So that the homologies between the sporophyte of the Musci 
and the sporophyte of the Vasculares may be thus tabulated :— 
Moscinez, VASCULARES. 
Sporophyte. Sporophyte. 
Epidermis .................. = Epidermis. 
Cortex GE = Cortex. 
Endodermis.................. =  Endodermis. 
Central strand, product ofendo-| _ j Axial vascular bundle or system 
meristem ............ eb of bundles. 
Leptophloém |.......... .... = Phloém. 
Functional bast. Functional bast. 
Leptozylem ........... T Xylem. 
Functional wood. Functional wood. 
ii. DEVELOPMENT OF THE SPoROGONIUM. 
The earliest stages of development, from the first division of 
the oospore to the formation of a fusiform embryo, and the later 
development of the spore-sac and theca, have been described by 
Kienitz-Gerloff (12) and Hofmeister (9) more or less completely. 
Therefore the development between these two stages only has 
been investigated for the purposes of this paper. 
According to Kienitz-Gerloff (12), the young embryo of Atri- 
chum undulatum grows in length by means of a two-sided apical 
cell; so that two series of semicircular segments are formed. 
Each segment is then divided by a radial wall into two approxi- 
mately equal parts. These walls are kuown as the quadrant- and 
octant-walls, the first formed being the quadrant-wall; those 
next formed at right angles to the quadrant-wall are the octant- 
walls. In transverse section, therefore, the circular outline of the 
sporogonium appears to be divided into four nearly equal sectors. 
Each quadrant at a later period, or lower down on the embryo, 
is diyided into three cells in such a way that there are two cells at 
the periphery and one at the centre (Pl. XII. figs. 41, 42); so that 
* Leptosporangiata, a class of Ferns. The force of lepto in this word is, I 
should think, a little doubtful : 
