1426 AGRICULTURAL BOTANY, CHEMISTRY AND PHYSIOLOGY OF PLANTS 



be combined with the insight of the inventor, no possible scientific method 

 can succeed without the intuition of the breeder. Any attempt to obtain 

 or record the characters of large numbers of plants and to obtain the final 

 selections by a scientific system of marks is hopeless, as the investigator 

 would be a speedily swamped by the volume of bis material. The insight 

 of the breeder is necessary for the work and the judgment, which comes by 

 practice, in the rapid summing up of essentials by eye is far more useful than 

 the most carefully compiled records or any system of score cards. The suc- 

 cessful plant breeder is to a large extent born and not made. Science helps 

 the born breeder by providing him with new and better instruments and, 

 by bringing knowledge to bear from many sides, it accelerates the output 

 and lightens the work in a multitude of ways. 



1066 - A Biochemical Study of Nitrogen in Certain Legumes. — whitixg, a. l. University 



of Illinois, Agi'icultuyal Experiment Station, Bulletin Xo. 179, pp. 471-512. Urbana, 111., 

 March 1915. 



The writer discusses the whole question of nitrogen fixation by legu- 

 minous plants and gives an account of his own experiments on the sub- 

 ject. These he divides into two parts : 



I. Studies to determine through ivhich organ legumes obtain atmos- 

 pheric nitrogen. The plants used were the soybean {Glycine hispida IMaxim) 

 and the cowpea [Vigna unguicnlata Walp). Uniform seeds were carefulh' 

 selected and inoculated with an infusion of B. radicicola. The plants 

 were grown in silver sand to which a nutrient solution was added, both sand 

 and solution being free from nitrogen. Wolf bottles were used as con- 

 taining vessels in order that the atmosphere around the roots should be 

 controlled, and whereas the roots of some plants were maintained in a 

 gas current consisting of 96 to 98 per cent of oxygen and 2 to 4 per cent 

 of carbon dioxide, others were maintained in a current of air. At the end 

 of each experiment the nitrogen was estimated in each plant, and the 

 amount fixed was determined. Results are given in Tables I and II. 



The error in soA^beans nos. I and 2 was partially accounted for by^ 

 a slight injury to these plants by grasshoppers and red ants. There was 

 also a small experimental error. The fixation shown by cowpea no. 2 

 was also attributed to a leak around the stem which prevented the Wolf 

 bottle from being gas tight. All plants receiving air had well developed 

 nodules. 



The experiments were repeated and the results were confirmed. In 

 order to test the viability of B. radicicola after exposure to the abnormal 

 atmosphere, infusions were made from the roots of plants grown in the 

 oxygen current and apj)lied to cowpea seeds that had been sterilized and 

 planted in sterile sand. Sterile conditions were maintained throughout 

 the test. Profuse nodule formation resulted, showing that the viability 

 of B. radicicola had been in no way impaired. 



Plants grown in the oxygen current usually developed two and some- 

 times three leaves before they seemed to be checked in their growth. Soon 

 an interesting tran.slocation set in. T^ach plant removed the nitrogen 

 from the lower leaves and developed a new leaf of a normal green colour^ 



