No. 3, April, 1921] PHYSIOLOGY 307 



Several pure, organic compounds of iron were used in pot experiments with soil but proved 

 to be poor sources of iron for small rice plants. Bulky organic compounds such as stable 

 manure, velvet bean plants, and tobacco stems when used in considerable quantity gave 

 increased yields over non-fertilized pots, and it is thought that more iron becomes available 

 from such sources.— The availability of iron is slightly greater when the soil moisture is at 

 optimum content for growth than when the soil is too wet, but certain calcareous soils 

 which commonly induce chlorosis in rice fail to do so when the soil is flooded.— D. Reddick. 



2123. Johnston, Earl S. Nutrient requirements of the potato plant grown in sand cul- 

 tures treated with "type I" solutions. Soil Sci. 10:389-409. 1 pi, 5 fig. 1920.- Potato 

 sprouts separated from the seed pieces were grown in sand cultures treated with 21 different 

 proportions of monobasic potassium phosphate, calcium nitrate, and magnesium sulphate. 

 The partial osmotic pressure varied by equal increments of | the total osmotic pressure of 

 1 atm. Cultures giving the highest yields were low in magnesium sulphate, high in calcium 

 nitrate, and medium in potassium phosphate. The lowest were low in calcium nitrate. The 

 average water requirement was 403. No relation between high yield and low water require- 

 ment nor low yield and high water requirement was noted.^H^. J. Robbins. 



2124. Pfeiffer, T., und A. Rippel. Der Einfluss von Kalk und Magnesia auf das Wach- 

 stum der Pflanzen. [The influence of lime and magnesia on the growth of plants.] Jour. 

 Landw. 68 : 5-39. 1920.— Experiments were made on oats in pots with clean, washed glass-sand 

 as substratum. Similar yields were produced when the molecular relationship of CaOiMgO 

 fluctuated between the limits 9:1 and 1:1 in 4 different series where increasing doses of CaO 

 and MgO were employed. The amounts of CaO and MgO taken up by the plants as found by 

 analyses led to the same conclusions as those from plant yields. The yield decreased when 

 CaO: MgO relationship increased from 1:1 to 1:9, interpreted as due to lack of lime neces- 

 sary to plant growth and not direct injury from MgO. Where the limit lies at which the un- 

 doubtedly existing antagonistic action between MgO and CaO begins to have a tangible, 

 practical significance was not established. Some indications (not confirmed) of the possi- 

 bility of substituting for CaO and MgO were noted. The CaO and MgO content of oat plants 

 varies within wide limits and is in part unusually high. The general rule that in the seed 

 MgO should be more important, and in the straw CaO, agrees with these experiments only 

 infrequently, and by no means universally. In opposition to other observations, an increas- 

 ing MgO content has not resulted in increased P2O5 accumulation. A certain relationship 

 between CaO:MgO:P206 in the sense used by Loew was not confirmed. The content of the 

 oat plant in K2O and especially in Na20. so far as determined, has a stationary value and does 

 not decrease under the influence of added amounts of CaO and MgO. The lime-potassium 

 law is not confirmed by the foregoing experiments.— C. E. Leighiy. 



2125. Pfeiffer, T., und W. Simmermacher. Die Kalkfeindlichkeit der Lupine. [The 

 aversion of the lupine to lime.] Landw. Versuchssta. 93: 1-47. 1919. — 'According to earlier 

 investigations, discussed in articles published in Mitt. Landw. Inst. Bresslau 6: 1911, and 7: 

 1914, it seemed that while the ill effects of lime upon the lupine were evidently due to the 

 plant's general sensitiveness to alkaline substances, there were indications that lime in itself 

 might be harmful regardless of its combination. It was concluded, however, that other fac- 

 tors might enter into the injury to lupines, such as reduction of phosphorus assimilation, 

 variations in assimilation of iron, and effect upon nodule-forming bacteria. To test these 

 points as well as to further study the effects of different lime compounds, the authors con- 

 ducted pot experiments. The results indicate that lime as calcium carbonate is beneficial 

 rather than harmful. The evidence regarding the effect upon nodule formation and phos- 

 phorus and iron assimilation is inconclusive. It is concluded that further investigations 

 along this line will be necessary. — A. T. Wiancko. 



2126. Rippel, August. Beitrag zur Kenntnis des Verhaltens der Aschebestandteile und 

 des Stickstoffs im herbstlich vergilbenden Laubblatt. [Contribution to a knowledge of the 

 behavior of the ash substances and nitrogen in autumn leaves.) Jahresber. Ver. Angew. Bot. 



