An Advance in Root Physiology 



127 



obtained from breeding operations; together representing reason- 

 able progress in the advancement of knowledge of a subject, 

 established by Darwin, whose own work upon it remains its 

 greatest contribution. 



AN ADVANCE IN ROOT PHYSIOLOGY. 

 By Burton Edward Livingston. 



Until very recently, the physiology of roots has almost 

 wholly failed to receive the attention of plant physiologists, 

 so much so, that we are at present more densely ignorant of 

 these organs than of any other equivalent portion of the plant. 

 This is somewhat surprising, in view of the important role un- 

 doubtedly played by the root system in plant activity, as well 

 as in view of the numerous and thorough investigations which 

 have been directed toward a real knowledge of the physiology 

 of the absorbing surfaces in animals. Happily, however, it 

 appears that the ordinarily invisible underground portion of 

 the plant is at length beginning to attract investigators, so that 

 a fair general knowledge of root physiology and of the relation 

 of these organs to the medium in which they grow may be 

 looked forward to with considerable assurance. 



Not the least important of the contributions in this direc- 

 tion are emanating from the workers in a laboratory not pri- 

 marily concerned with physiology, namely that of the Bureau 

 of Soils of the U. S. Department of Agriculture. During the 

 the past decade these investigators have been led to the view 

 that any real knowledge of the agricultural properties of soils 

 must develop hand in hand with a knowledge of root physiology. 

 Thus there has already resulted a modern investigation of the 

 old theory of DeCandolle, that growing plants excrete poisonous 

 materials from their roots. Bulletins 28, 36, 40, etc. of the 

 Bureau of Soils present data which practically establish the two 

 propositions, that poor agricultural soils often contain harmful 

 substances (probably of organic nature), and that growing roots 

 of wheat actually produce poisons in the medium in which they 

 are grown, these latter possessing a marked similarity in their 

 physiological effect to those demonstrated as occurring in the 



