SPHAGNALES 



273 



of tissue with rounded apex (Fig. 133 F, H). The peripheral series of 

 cells, or amphithecium, divides periclinally to give off internally the single 



FIG. 132. 



Development of sporogonium of SpJtagnum acutifplium, Ehrh. A = embryo with four 

 tiers; J = apical cell; =basal cell with oblique division. j6? = embryo with five tiers. 

 C = optical section of the same embryo; one quadrant is still undivided; rt = anticflnal; 

 / = periclinal walls; h = principal walls. D transverse section of the lower part of an 

 embryo. E = & rather older stage; spr = spore-forming layer. ,F=median longitudinal 

 section of a sporogonium showing the bell-shaped sporogenous layer, and the wall covering 

 it externally. G = transverse section of a sporogonium of similar age ; lettering as in E, 

 // = median longitudinal section, though a half-ripe sporogonium; ca/=calypira ; spr 

 spore-cavity, in which the spore-mother-cells are isolated ; sps = spore-sac ; epi = epidermis ; 

 7 = furrow in wall where the operculum will separate ; / > j = pseudopodium ; ^ = vaginula ; 

 ^W=perichaetial leaves ; co/=coluinella. (After Waldner, from Engler and Prantl.) 



layer of the archespo'rium ; this appears as a continuous dome closely 

 investing the columella. The external product of the amphithecium forms 



s 



