PLANT-CELLS AND THEIR CONTENTS. 



295 



into forms organic, and the earth filled with the children of life, the 

 very essence of the living cell the protoplasm. To this protoplasm 

 we now turn our investigation. 



Twelve or thirteen years ago this word the name, to say nothing 

 of the thing named would have come all but unknown to the general 

 reader. But to-day, thanks to the continuous discussions of the last 

 decade, the word needs no introduction. All our readers know that 



Fig. 8. Cross-Section of Petiole op Begonia-Leap, shows Crystals in the Cells (copied 



from Prantl.) 



protoplasm is the simplest form of living matter with which we are 

 acquainted, is the living element of every living cell. One of the 

 most characteristic phenomena of life is independent motion, and pro- 

 toplasm more frequently reveals itself by moving. Such is the case in 

 the cells we are now considering. In 1869 Professor Huxley set the 

 thinking world all agog by describing, in a passage of wonderful accu- 

 racy and beauty, what he could see of moving protoplasm in the hair of 

 a stinging nettle. Nettle-hairs and vegetable hairs generally consist 

 either of a single elongated cell, or of a series of oblong cells arranged 

 in a filament. Moreover, such hairs, or trichomes, are usually colorless, 

 transparent throughout, and afford, therefore, cells admirably adapted 

 to microscopic examination. Hairy plants are very common, so we 

 may corroborate Professor Huxley's statements by observations made 

 almost anywhere. Let us examine a hair taken from the evening-prim- 

 rose. Here, under a magnifying power of from 400 to 500 diameters, 

 we may see within the hair a delicate current sweeping down one side 

 to the point, turning abruptly with slight delay, and then returning by 

 the opposite side of the cell, leaving in the center a neutral space filled 

 with cell-sap, across which the oppositely moving streams seem never 

 to pass, in which they are never lost. No nucleus is present, nor any 

 central station of power. The tiny streamlet pours on, self -guided 



