BOTANY. 811 



is probably duo to the presence of organic acids and other substances in the rhizoids 

 thai show great affinity for water. Although the organic acids increase in the cells 

 at 50 to 60° F., yet their increase does not seem to make any appreciable difference 

 in the periodicity. This is true even when the temperature of the soil is brought 

 up to 55° F., approaching the time of minimum pressure. 



"The fact that seems inexplicable is that, when the temperature is raised above 

 the point where the organic acids decompose (60° F.) in most plants, the roots may 

 show an increase in their osmotic activity at the daily period of maximum pressure. 

 The absence of a top to the plant and its consequent loss of periods of maximum 

 and minimum oxidation, which are the real causes of the variation in the quantity 

 of organic acids in the cell, may be the reason for the failure to produce the expected 

 results. The time of periodicity of root pressure is constant in the same genus, but 

 some species may show greater absolute pressure than others. This may be due to 

 accidents in growth, etc. The fact of the periodicity of root pressure seems to be 

 established beyond the possibility of a doubt, and capillarity and similar phenomena 

 can not account for the facts observed.'' 



The amount of nitrogen conveyed by red clover to different 

 kinds of soil, N. PA8SERiNi(/>or. Scuola Agrar. Scandicci, 1895, No. 3, 

 pp. 102-111 ; abs. in Jour. Chem. Soc. [London], 72 (1897), No. 121, II, 

 p. 587). — A report is given of experiments with red clover grown in 

 wooden boxes containing 3 different kinds of soil — sandy, clayey, and 

 calcareous. There was a decided loss in nitrogen in the soil at the end 

 of the experiments in the case of the sandy and clayey soils, but a gain 

 in the calcareous soil. The loss is at least in part attributed to a loss 

 of nitrates in drainage and possibly a less active fixation of nitrogen. 



Nitrogen nutrition of the LeguminosEe, K. von Rozdejczer 

 (Inaug, Diss., Leipzig; abs. in Jour. Chem. Soc. [London], 72 (1897), No. 

 421, II, pp.586, 587). — A report is given of experiments in which peas 

 were grown in sandy, loamy, and humus soils. There were 3 scries of 

 experiments. In the first the pots were un manured, in the second they 

 were manured with mineral manure and sodium nitrate, and in the 

 third with mineral fertilizer without sodium nitrate. The pots were 

 kept in the open air except during very wet weather, and the amount of 

 nitrogen in the rain and water used was determined. 



On taking up the plants the greatest tubercle development was found 

 in the pots which had received chemical fertilizers and in the unma- 

 nured sandy soil, the development being slight in the loamy and humus 

 soils and very poorly represented in the pots receiving sodium nitrate. 

 A summary shows the average amount of nitrogen in the soil, seed, 

 and produce, and also the gain or loss at the end of each experiment. 

 A gain in nitrogen was indicated in every series except that of the 

 loamy soil which received the sodium nitrate, in which there was ;i loss. 



The author concludes that with insufficient nitrogen in the soil peas 

 assimilate considerable amounts of free nitrogen, but with an increased 

 supply of soil nitrogen the power of fixing free nitrogen diminishes, 

 the plants utilizing the combined nitrogen of the soil. With rich soils 

 elementary nitrogen is either not utilized at all or in very small quan- 

 tities. The author states that leguminous crops should be well manured 

 with potash and phosphoric acid. 



