MICROSCOPIC OBJECTS. 13 



Fig. 25. Siliceous Cuticle of Bearded Darnel-grass (Lolium 

 temulentum) , x 240. 



This cuticle is taken from the Bearded Darnel, or Rye- 

 grass. When this grass grows in great quantities, as it does 

 occasionally, it is said to be very injurious to grazing cattle. 

 In the Grasses, Equisetacese, &c. the cuticle is almost always 

 strengthened by a deposit of pure silex, which may be easily 

 tested by burning a wheat-straw, when the original form 

 remains, which would not be the case if the cuticle had not 

 contained silex. Siliceous cuticles may be prepared by boil- 

 ing the stems for a long time in nitric acid ; but if the object 

 to be prepared is weak in silex, the acid must be diluted 

 with one-third part of water ; it may then be well washed in 

 water, and mounted in liquid, or dried and then mounted 

 in balsam in the ordinary manner. 



Fig. 26. Ramenta, or Scales, from a Fern (Nothoclsena 

 Isevis), x60. 



These scales are drawn as shown under polarized light. 

 On the creeping stems of various species of Ferns, or on the 

 leaf-stalks of scaly kinds, bodies may be found, which are 

 in this case called r amenta (Latin ramentum, a shaving). 

 In structure these membranous bodies appear to be closely 

 allied to the scales in fig. 27, the chief difference being 

 the point of attachment and the well-marked network of 

 the cells. The common Scale-Fern (Ceterach qfficinarum) 

 owes its remarkable appearance to these ramenta, or scales. 

 The stipes of the male Fern (Lastrea filix-mas) , and various 

 other British species of Fern, are covered with them. 



They may be mounted dry or in liquid ; but if required for 

 the polariscope, in Canada balsam, or sometimes in glycerine. 



