Physiologie. 339 



was determined from the following calculation: A good crop of 

 clover should yield from 4 to 5 tons of undried green hay per acre. 

 If one acre of soil 3 inches deep weighs 1,000,000 pounds, then 1 

 per Cent of green clover is comparable to the ainount employed 

 under field conditions. Except in rare cases this amount of green 

 manure was used in all of the laboratory studies. The green plant 

 tissue was cut just before blooms began to form, finely chopped, 

 and mixed thoroughly with silt loam soil. The soil moisture was 

 maintained at 50 per cent Saturation. All tests of germination are 

 recorded in percentages. In this manner the following conclusions 

 were obtained: 



Green manures may seriously injure the germination of cer-taitt 

 seeds. 



This injury is brought about by the action of certain parasitic 

 fungi. 



In the first stages of decomposition of green clover, numerous 

 fungi develop. Some of these fungi are very destructive to 

 seedlings. 



Oil seeds as a class are very easily damaged by fungi. Starchy 

 seeds, on the contrary are very resistant. 



Cotton seeds {Gossypiunt herbaceu^n) and soybeans {Glycine 

 soya) are examples of seeds extremely sensitive to green manuring. 

 The germination of flax [Linum usitatissimum) , peanuts {Arachis 

 hypogea), hemp [Cannabis sativa), white mustard {Brassica alba) and 

 clover is reduced in the presence of decomposing plant tissue, but 

 not to as great a degree as that of cottonseed or soybeans. The 

 germination of buckwheat {Fagopyrum tataricum), corn {Zea mays), 

 oats {Avena sativa) and wheat {Triticum sativum) is not affected by 

 green manures. 



The damage to oil seeds from green manures is confined lar- 

 gely to the first stages of decomposition. Experimental evidence 

 Shows that two weeks after green manure is added it does not cause 

 any serious injury to the germination of oil seeds. 



Small applications of calcium carbonate seemed to increase the 

 injury to germination. 



The rate of germination determines to a certain extent the de- 

 gree of injury. Slow germination is marked by a high percentage 

 of diseased seedlings. M. J. Sirks (Wageningen). 



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

 from certain nutrient Solutions. (Journ. agr. Research. 

 Washington. VII. p. 503-528. 1916.) 



As calcareous soils have a slightly alkaline reaction itisimpor- 

 tant to know whether plants intolerant of calcareous soils are sen- 

 sitive to an acid or alkaline reaction per se, and whether the 

 reaction of the soil has any eflfect on the assimilation ofiron. Various 

 experiments with upland rice {Orysa sativa) in nutrient Solutions 

 and soil cultures have been conducted by the writers to gain Infor- 

 mation on this subject. The experiments with nutrient Solutions are 

 reported in this paper; they show the effect of the quanlity and 

 form of iron and reaction of the nutrient medium on the assimila- 

 tion of iron by rice. 



The riceplants were grown in acid, neutral and alkaline Solu- 

 tions with different forms and quantities of iron. In nearly all cases 

 growth was much better in the nutrient Solutions employed with 



