ELATEItS OF JUNGERMANNIA. 41 



ELATERS OF EQUISETUM. 



This slide is useful chiefly in directing attention to the 

 plant from which the elaters are taken, and as leading the 

 student to an interesting experiment. 



The Equisetacese, or Horsetails, are leafless plants found 

 on moist ground, in ditches and rivers, with whorls of long 

 slender branches, and a hollow stem which gives the micro- 

 scopist a very beautiful siliceous cuticle with stomata. The 

 fructification is found in the spring : a fertile scaly head 

 rises from the earth, having circles round it of shield-like 

 discs, beneath which the spore-cases and these spores, which 

 then appear only as a fine green dust, lie concealed. 



Shake a little of the dust on a slide of glass, and innu- 

 merable small bodies will be seen, each with four elastic 

 filaments clasping and unclasping them in quick motion 

 for several minutes. If dry and motionless, by lightly 

 breathing on them the action will be repeated. These are 

 the elaters of the Equisetum, and the mechanism by which 

 the spores are dispersed. 



ELATERS OF JUNGERMANNIA. 



Jungermannia, or Scale-moss, is a plant of lower rank 

 in the vegetable world than the true moss, such as Dicra- 

 num or Funaria. The elaters which are here mounted 

 belong to that species called Jungermannia dilatata, which 

 creeps over the bark of trees, and tints the trunk of' an old 

 elm or oak with a rich brown or crimson ; here and there a 

 patch of this scaly plant encrusting the rugged surface, and 

 requiring the aid of a pocket lens to see its fructification. 



Any time from November to March look closely at one 

 of these dark masses, and you will see dotted over it tiny 

 globes, white as of frosted silver, rising on a slender stem, 

 and perhaps great numbers of exceedingly minute fawn- 

 coloured flowers. If you gather one and examine it with 

 a good glass, small tufts of spiral fibre will be seen on each 

 segment of what seems to be a flower these are the elaters. 

 Now this is not a flower,- but a simple spore-case. The 

 little white globe before noticed splits into four valves, 



