1917] AGEICULTURAL BOTANY. 631 



nutrient solutions produced varying results for the different species grown in 

 both sand and water cultures. The rapidity of the absorption of the different 

 compounds varied with the different plants, and an excess in the solution of 

 any given material was not shown in its increased accumulation in the plants. 

 The quantities of the various elements absorbed and assimilated were not 

 always the same. 



The efifect of repeated growing' of plants in nutritive solutions, E. A. 

 Zhemchuzhnikov (Gemtchougenikov) {Iz RezuVt. Veget. Opytov Lab. Rabot 

 {Rec. Trav. Lab. Agron.), Moskov. Selsk. Khoz. Inst., 10 (1914), pp. 327-354, 

 pi. 1, figs. S). — Experiments are reported with a number of species of plants re- 

 seeded in sand cultures in which the same species had been previously grown. 



The results showed that the growth was inversely proportional to the alka- 

 linity of the solutions resulting from growing the previous crops. Where the 

 nutrient solutions contained nitrates such as are recommended by Hellriegel, 

 Knop, Crone, and others, the alkalinity was more pronounced and the growth 

 more rapidly diminished than where ammonium nitrate was employed as a 

 source of nitrogen. 



The influence of the alkalinity of a solution on the transformation of 

 nitrogenous material in germinating peas, V. A. MoKozov (Morosov) (Iz 

 RezuVt. Veget. Opytov Lab. Rabot (Rec. Trav. Lab. Agron.), Moskov. Selsk. 

 Khoz. Inst., 10 (WW, pp. 384-389, fig. i).— The author claims that the al- 

 kalinity of the nutrient solution retards the transformation of nitrogenous 

 materials contained in seeds without changing the process. 



The significance of the potassium ion in the synthesis of nitrogen com- 

 pounds in the plant cell, J. Stoklasa (Biochem. Ztschr., 73 (1916), No. 1-2, 

 pp. 107-160). — In continuance of previous work (E. S. R., 25, p. 125), the author 

 has studied the r61e of potassium ions in the synthesis of nitrogen compounds, 

 employing the sugar beet as well as bacterial cultures for this purpose. 



It is thought that the potassium ion is concerned in the formation of nitroge- 

 nous materials in the bacterial cell, probably being connected with condensation 

 and catalytic processes. In case of beets kept under illumination in an atmos- 

 phere free from carbon dioxid and supplied with carbon in the form of glucose, 

 fructose, or saccharose, nitrogen compounds are formed by them both in the 

 presence and in the absence of potassium ions. When the supply of plastic 

 organic compounds in the cell is abundant, and there is solar illumination, 

 nitrogen compounds may form without the presence of potassium, and they 

 may form without sunlight in the presence of abundant potassium, carbon 

 sources, and inorganic nutrients in the cell. Without potassium and in dark- 

 ness, nitrogen compounds are not synthesized, even when the carbohydrates 

 are abundant in available form. On complete exclusion of light, the potassium 

 ion appears to serve as a source of energy and to condition the formation of 

 carbohydrates through the action of respiratory enzyms. The processes of for- 

 mation of new living cells and of dissimilation appear to be related in some 

 way. Potassium is thought to play an important part in dissimilation and in 

 physiological combustion and, in connection with light, to bring about catalytic 

 reactions and photodynamic effects. 



The role of calcium carbonate in the assimilation of ammonia, V. A. 

 MoKozov (MoRosov) (Iz RezuVt. Veget. Opytov Lab. Rabot (Rec. Trav. Lab. 

 Agron.), Moskov. Selsk. Khoz. Inst., 10 (1914), pp. 390-395).— The author has 

 studied the effect of replacing calcium carbonate by ferric hydroxid. He has 

 found that If the etiolated plants received ammonium sulphate as a source of 

 nitrogen, the results were favorable to the addition of ferric hydroxid, but the 

 action of calcium carbonate was more energetic. 



