220 



Methods in Plant Histology 



green. Safranin and Delafield's haematoxylin is also an excellent 

 stain for the older stages in the differentiation of the capsule. 



The mature sporophytes of Sphagnum (Fig. 72) are exceptionally 

 hard to cut. It will be worth while to prick the capsule with a 

 needle when the material is collected. This will allow the fixing 



FIG. 71. Bryum: portion of nearly 

 mature capsule showing operculum, an- 

 nulus, peristome, and three cells of the 

 sporogenous tissue. X200. 



FIG. 72. Sphagnum: longitudinal 

 section of sporophyte showing also 

 the upper portion of the pseudo- 

 podium and the calyptra Dela- 

 field's haematoxylin. X24. 



agent to penetrate readily, and will also facilitate the infiltration of 

 paraffin or celloidin. The puncture causes only a slight damage, 

 and need not reach the really valuable portion which is to furnish the 

 median longitudinal sections. 



The younger stages in the sporophyte of Sphagnum, and also 

 the antheridia, archegonia, and the peculiar development of the 

 leaves are easily cut in paraffin. 



