34 THE MICROSCOPE. 



is acquainted with those curious-looking plants called 

 horsetails (Equisetacea) ; you will find them interesting 

 microscopic studies. Take hold of one ; you notice 

 how rough it is ; this roughness is caused by a quantity 

 of silex which permeates the whole of the structure of 

 the horsetail. To such an extent does this in some 

 cases take place, that " even when its organic portion 

 has been destroyed by prolonged maceration in dilute 

 nitric acid, a consistent skeleton still remains/' These 

 horsetails are reproduced from spores on a spike at 

 the end of some of the branches. To each spore are 

 attached two pairs of elastic filaments; at first they 

 are coiled up round the body of the spore ; at the 

 liberation of the spore they extend themselves. " If a 

 number of the spores be spread on a slip of glass 

 under the field of view, and whilst the observer 

 watches them a bystander breathes gently upon the 

 glass, all the filaments will be instantaneously put in 

 motion, thus presenting an extremely curious spectacle, 

 and will almost as suddenly return to their previous 

 condition when the effect of the moisture has passed 

 off."* I have frequently witnessed this curious spec- 

 tacle, and you can easily do so yourself by following 

 Dr. Carpenter's directions, which I have just quoted. 

 The Equisetacecz develop themselves from these spores 

 after the manner of ferns ; on this account the name 

 " fern allies " has been applied to their family. 



You will find endless variety of form and markings 

 in the seeds of plants. Seeds as microscopic objects 

 under a low power and by reflected light, or viewed 

 under the binocular, are often extremely beautiful. 

 Take the seed of the poppy ; notice the network 

 markings upon its surface ; or the seed of the carrot 

 with its long starfish-like radiating processes. Make 



* Carpenter, p. 383. 



