272 MR. J. R. VAIZEY ON THE ANATOMY AND 
the peculiar form of the lips of the stomata of Polytrichum 
(Pl. X. figs. 18, 20) ; compare also Haberlandt (6), Taf. xxvi. 
The stomata of other Musci are, in those forms in which 
they are known, according to Haberlandt's and my ‘own obser- 
vations, similar to the stomata of the higher plants (Pl X. 
fig. 27). Stomata have been seen in all stages of development; 
and these observations show that the cell-plate is at no period 
complete in Polytrichum. This form of stoma is found also in 
Funaria (Pl. X. fig. 19) and in some Angiospermatous Phanero- 
gams, e. g. Profea sp., according to H. von Mohl (19). In all 
other forms in which the stomata have been observed, they have 
the normal form found in vascular plants. 
In the Antherocerotee—the one Order of the Hepatic» which 
have stomata on the sporogonium—I have found them to be of 
the typical vascular form (Pl. X. fig. 24, 25); also in the following 
Musci :—Mnium hornum, Hedw. (Pl. X. figs. 26, 27), Dicranum 
scoparium, Hedw., and Splachnum vasculosum, Linn. (fig. 29) ; and 
Phascum cuspidatum, Schreb., according to Kienitz-Gerloff (12)*. 
Underneath the epidermis of the apophysis the cortical 
tissue of the sporogonium is much more strongly developed ; in 
fact, nearly the whole of the extent to which the apophysis 
exceeds the diameter of the seta is due to increase in cortical 
parenchyma. The cells of this tissue are here closely packed, 
only leaving small intercellular spaces, except immediately under 
the stomata, where large intercellular air-passages are found 
(Pl. IX. fig. 9; Pl. X. figs. 13, 18, 20-23). In transverse section 
ihe cortical parenchyma is seen to be arranged in rows of cells 
radiating from the “central strand” to the epidermis. These 
cells are elongated in a radial direction (Pl. IX. fig. 9). Their 
exact arrangement can be best understood by comparing the 
transverse (fig. 9) with the longitudinal section (Pl. X. fig. 13). 
The cell-walls are for the most part thin, except those just 
underneath the epidermis (Pl. X. fig. 18), which are slightly 
thickened. 
In transverse as well as in longitudinal section the development 
of a bilateral symmetry is evident (Pl. IX. fig. 9, Pl. X. fig. 13). 
In transverse section the “central strand” is seen to occupy & 
position much nearer to the posterior side of the apophysis than 
io the anterior, and equidistant from the two flanks. The 
* To this list may beadded Mnium cuspidatum, Hedw., Splachnum ampulla- 
ceum, Linn., and some others more or less modified, according to Haberlandt (6). 
