640 



Journal of Applied Microscopy. 



that it is better to use harder paraffin (55° to 6-0°C.) and make an effort to get 

 preparations from chromic material. 



Stages like that shown in Fig. 9 are cut with comparative ease, for the 

 calyptra is easily removed and the capsule wall is not yet hard enough to 

 occasion any difficulty. The cell walls are so easily stained in moss capsules 

 that a light counter stain with erythrosin or acid f uchsin may be used to bring 

 out the cytoplasm and plastids without appreciably obscuring the cell walls. 

 Funaria and Bryuni afford an excellent study in the development of the capsule, 

 since all the structures of a highly differentiated moss sporophyte are present, 

 and Bryum is particularly easy to cut in stages like those shown in Fig. 10. 



Fig. g. Funaria hygrometrica. X 420. 



A. Longitudinal section of capsule. B. Transverse section of capsule of about the same age as A. The 

 columella, archesporium, outer spore case, two layers of chlorophyll-bearing cells, and the begin- 

 ning of the air spaces can be distinguished at this stage. Delafield's haematoxylin 

 and erythrosin. Ten microns. 



Sporophytes, in their more mature stages, are almost sure to present con- 

 siderable difficulty in cutting. For general work fairly good preparations may be 

 gotten from celloidin material, but it is worth while to try paraffin, for it is some- 

 times successful, and when it does succeed it is far superior. As soon as the 

 cell walls begin to thicken, as in the development of the peristome, safranin is 

 an excellent stain and this, followed by Delafield's haematoxylin, will give an 

 elegant differentiation in the older stages of the sporophyte. 



The mature sporophytes of Sphagtiuvi 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 agent to penetrate readily, and will also facilitate the 



