34 



upon the cells ' of plants, and, also, upon the func- 

 tions of the bacteria concerned in feeding nitrogen 

 to plants ? 



In these early days of the X-rays of Roentgen, 

 let us wonder what effect they may have, not only 

 on plants above the soil, but especially on the roots 

 and bacteria in the soil, which soil the rays can 

 penetrate to a considerable depth. 



So far experiments have not been conclusive. 

 Professor Atkinson states that while plantTtissues 

 absorb the Roentgen rays quite freely, there is no 

 marked influence on the growing parts, and, also, 

 that bacteria are negatively affected. Other ex- 

 perimenters report that exposure of the bacillus 

 prodigiosus to the radiations of an X-ray focus-tube 

 induces very marked increase of growth and pecu- 

 liar changes in the pigment-forming powers of this 

 particular micro-organism. Similar changes were 

 noted in some of the lower forms of vegetable life, 

 notably in the protococcus. 



1 Stanoievitch, a Russian scientist, has made the interesting 

 observation that the markings produced by growth on a sec- 

 tion of wood or vegetable, are very similar to those produced 

 by sifting iron filings upon a plate of glass and holding the 

 poles of a magnet directly under it. And he argues that there 

 is an analogy between the actions of plants which arrange 

 their cells in such definite positions, and the play of the magnet 

 which makes the familiar " lines of force." 



