FIELD CROPS. 771 



The distribution of water was quite uniform in all parts of the plant up to the time 

 of heading, when the percentage of moisture in the part above ground began to fall 

 below that of the root system. The water content of the entire plant, however, 

 decreases from the beginning of growth in the fall, the rate of decrease being very 

 low until spring, when the reduction goes on more rapidly as the plant develops. 

 During the progress of growth the percentage of dry matter, nitrogen-free extract, 

 and crude fiber increases, while the percentage of water, nitrogen, proteid substances, 

 am ids, fat, and ash decreases. 



In the corresponding experiments with wheat it was found that 100 plants on 

 April 22 weighed (3^ times as much as they had weighed at the end of October. The 

 increase in weight was equally divided between dry matter and water, and was greater 

 in the part of the plant above ground than in the roots. The percentage of nitrogen- 

 free extract and crude fiber was much higher in the spring than in the fall, and con- 

 sequently these substances took part in increasing the weight of the plant. The 

 mineral constituents also showed an increase corresponding to the increase in dry 

 matter. The assimilation of nitrogen did not keep pace with the production of dry 

 matter. The nitrogen taken up was used more extensively in the formation of pro- 

 teids than of amids. During this period the amid supply of the roots moved into the 

 portions above ground. 



From the beginning of further development in the spring until the heads appeared, a 

 period of 55 days, assimilation of plant food was carried on very actively. Eighty 

 per cent of the dry matter elaborated during this period consisted of nitrogen-free 

 extract and crude fiber. The amids were transferred from the roots to the upper 

 portion of the plant, where they were transformed into proteid substances. The 

 mineral substances were translocated in the same manner. 



After the amids have been removed the roots of both wheat and rye seem to act 

 during winter as storehouses of nitrogen-free substances. The heads in the early 

 stage of their formation were relatively rich in nitrogen compounds, especially amids, 

 and in readily soluble potassium phosphate. In the spring the roots contained a 

 little less moisture than in the fall and the reduction of the moisture content of the 

 plant in its relation to dry matter began with growth in the spring. As in the 

 case of rye, a percentage increase occurred only in the dry matter, the nitrogen-free 

 extract, and crude fiber, while the percentage of ash and of sulphuric acid, lime, and 

 magnesia in the dry matter remained constant. All other constituents decreased in 

 percentage content as the plant developed. 



In comparing the results with the two crops it was found that at the close of winter 

 the rye had taken up almost one-half of its nitrogen content, while wheat took up 

 most of its nitrogen from the end of April to the time the kernels began to form. 

 Wheat continued to take up nitrogen when the plants were heading, while rye no 

 longer took up this element from the soil at this stage. This shows that rye should 

 be provided with readily soluble nitrogen compounds during the winter, and that 

 both cereals should be given an abundant supply at the beginning of growth in the 

 spring. Phosphoric acid was taken up during the period of intensive spring growth 

 and until the plants headed out, with perhaps, in the case of wheat, until blossoming. 



Potash was used by both crops during the winter, but the largest quantities of 

 this element were used from the beginning of growth in the spring until the heads 

 appeared. The greatest use of potash was simultaneous with the most active forma- 

 tion of carbohydrates and cellular tissues. Lime and magnesia were used in only 

 small quantities by the young plants, but the needs for these substances increased 

 as the plants developed, and it is believed that this greater need is connected with 

 the hardening of the tissues. 



The cereals in America, T. F. Hunt {New York: Orange Judd Co.; London: 

 Keijun Paul, French, Trubner & Co., Ltd., 1904, pp. 4&1, pi. 1, figs. 149).— This book, 



22868— No. 8—05 4 



