136 CLOVER CULTURE. 



seed was about exhausted, Nos. 13 and 14 began to fail. For 

 a few days after this no perceptible difference could be noted 

 in the growth of the other plants. No. 12 then dropped behind 

 an a few days later Nos. 9, 10 and 11, and, after a short inter- 

 val, all the others up to No. 1 could be identified by their ap- 

 pearance, so that in a month from the time the first plants 

 appeared the row of pots showed clearly which had received 

 the larger amounts of nitrogen. This was manifest not merely 

 in the height and general vigor of the stalk, but in the num- 

 ber of shoots or stools put forth. No. 1 put out five shoots- 

 or stools; Nos. 2, 3 and 4 put out four, one only of them bear- 

 ing a head ; No. 5, from three to four, one bearing a head ; 

 the remainder from one to two, but all failed to head. Later 

 on, however, the main stalk consumed the side shoots to build 

 itself up. The next lower also consumed their earlier-formed 

 parts in their effort to develop heads. The results of this- 

 experiment with a non-leguminous plant are only what might 

 have been expected, inasmuch as it has been repeated over 

 and over again and always with the same result, namely, that 

 within certain limits the yield of the cereals or non-leguminous 

 plants is dependent upon the amount of nitrogen in the soil 

 available for the plant. 



x Having thus demonstrated that the cereals were abso- 

 lutely dependent upon the amount of available nitrogen in 

 the soil, Prof. Helriegel conducted a series of elaborate 

 experiments with the legumes, of which we give one typical 

 case. Fourteen pots were selected, identical with the others, 

 the soil material, the manner of filling and the fertilizers 

 being precisely the same. No. 66 having the same amount 

 of nitrogen as No. 1 in the barley experiments, and Nos. 77, 

 78 and 79 corresponding in amount to Nos. 13 and 14 of the 

 barley table, or, in other words, with no nitrogen. ^The 

 plants all came up well and evenly, and there was no differ- 

 ence in the pots up to the end of the second week. The third 

 week there was a difference not only in growth, but in color. 

 Those that had no nitrogen were somewhat higher and of a 

 somewhat greener color, while those that had been fertilized 

 with nitrogen were darker, and the more nitrogen, the darker. 

 The fourth week a difference in the development began to 

 appear. -Pots 77, 78 and 79 fell back, showing signs of 

 nitrogen hunger. The new leaves were smaller and they 

 seemed to be formed by pumping out and drying up of the 

 lower leaves. The numbers grew normally and by the end of 

 the sixth week the whole row of experimental pots very 

 accurately reflected in their condition and appearance the 

 amount of nitrogen each had received. During the seventh 



