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 



H 



Development of sporogonium of Sphagnum aciitifoliuin, Ehrh. A =cjmbry< i u iih four 

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

 C = optical section of the same embryo; one quadrant is still undivided ; = anticr5nal ; 

 ^ = periclinal walls; A = principal walls. Z? = transverse section of the lower part nl an 

 embryo. R & rather older stage; spr = spore-forming layer. ^"=median longitudinal 

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

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

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

 spore-cavity, in which the spore-mother-cells are isolated ; .r/j = spore-sai ; <// pidui mis ; 

 (/furrow in wall where the operculum will separate; /".!= pseudopodium ; - 1 vaginula ; 

 //'/=perichaetial leaves ; c<7/=columella. (After Waldncr, from Knglui and Prantl.) 



layer of the archesporium ; this appears as a continuous dome closely 

 investing the columella. The external product of the amphithecium forms 



s 



