CHAPTER V. 



ROOTS AND ROOT- HAIRS. 



Older views as to root-hairs Root-hairs and their de- 

 7'elopment Stirface Variations Conditions for 

 maximum formation Minute structure Adhesion 

 to particles of soil Functions. 



On the roots of most plants are to be found 

 delicate, silky-looking, tubular prolongations of 

 some of the superficial cells, known as root-hairs. 

 Malpighi (1687) seems to have been the first to 

 observe them, and he took them for capillary 

 tubes. Grew (1682) seems to have been responsible 

 for the view that the roots act like sponges in 

 taking up water. 



Simon (1768) was probabl}- the originator of the 

 idea that these root-hairs were excretory tubules, a 

 view that became very popular at the beginning of 

 this centur)'. 



Meyer (1838) was perhaps the first to give a 

 comparative account of them, and he supposed 



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