294 Physiologie. 



tive effects of different soil types are not specific and constant, but 

 depend largely on seasonal conditions 



From the data in hand it is concluded that under practical con- 

 ditions climate is a more patent factor than soil type in Controlling 

 the size of the seed and its oil content, probably because those 

 conditions of the atmosphere which constitute the climate largely 

 control the corresponding conditions of the soil. 



Within ordinary limits the relative fertility of the soil appears 

 to be a minor factor in influencing the size of the seed and its oil 

 content. In fertilizer tests with cotton the addition of a complete 

 fertilizer to an unproductive soil gave larger seed and a consider- 

 ably higher percentage of oil. Applications of nitrogen in increasing 

 quantities did not affect the size of the seed, but lowered the per- 

 centage of oil, while increasing applications of phosphorus or potas- 

 sium did not affect either character. In potculture tests with soy 

 beans the addition of phosphorus did not change the size of the 

 seed, but increased the oil content. Potassium was without decided 

 affect. In similar tests with peanuts neither phosphorus nor potas- 

 sium affected the oil content. M. J. Sirks (Haarlem). ■ 



Gile, P. L. and J. O. Carrero. Assimilation ofcoUoidal 

 iron by rice. (Journ, agr. Res. Washington. III. p. 205-210. 1914.) 



According to the results of their investigations, the writers 

 think, that their work would seem to show that rice can not 

 assimilate coUoidal iron. It is believed that the iron obtained from 

 the dialyzed-iron preparation was soluble iron. 



It is apparent that the toxicitj^ of ordinary distilled water or 

 ferric-chlorid Solutions for plant roots can not be overcome by 

 supplying other roots of the same plant with a balanced Solution. 



The toxicity of the ferric-chlorid Solution was accompanied by 

 the Penetration of iron into the root and transpiration to the leaves. 



M. J. Sirks (Haarlem). 



Hasselbring, H. and L. A. Ka'wkins. Physiological changes 

 in sweet potatoes durin g storage. (Journ. agr. Res. 

 Washington. III. p. 331 — 342. 1915.) 



The authors give following summary of their researches: 



During its growth the sweet-potato root is characterized by a 

 very low sugar content. The reserve materials from the vines are 

 almost whoUy deposited as starch. 



Immediately after the roots are harvested there occurs a rapid 

 transformation of starch into cane sugar and reducing sugars. This 

 initial transformation seems to be due to internal causes and is 

 largely independent of external conditions. Even at a temperature 

 of 30° C. both cane sugar and reducing sugars accumulate during 

 this initial period in excess of the quantity used in respiration, 

 while during subsequent periods the quantity of reducing sugar 

 diminishes at that temperature as a result of respiration. These 

 initial changes seem to be associated with the cessation of the flow 

 of materials from the vines. 



In sweet potatoes stored at a temperature of 11.7'^ C. to 16.7° C, 

 the moisture content remains fairly constant. There is a gradual 

 disappearance of starch during the first of the season (October to 

 March) and probably a re-formation of starch accompanied by a 



