34 EXPERIMENT STATION RECORD. 



to a rise of the organisms from lower depths, or whether the low temperature 

 or high moisture content of winter soil favor bacteria. 



In the experiments with aerated and unaerated soils in pots, tests were made 

 of two types of soil that had been cropped recently. It was found that the 

 number of bacteria in frozen soil is generally larger than in unfrozen soil. 

 The increase after freezing is not due to an increase in soil moisture, and it 

 took place in potted soil where there was no possibility that the bacteria 

 could be brought up from lower depths. 



Discussing the general results, the author offers a number of explanations, 

 among them a dependence on low temperature rather than increase in soil 

 moisture. Also the increase may not be an actual multiplication, but a libera- 

 tion of a large number of colonies that would not be otherwise recognized. If 

 the increase is due to actual multiplication It might imply that soil organisms 

 are able to use congealed water in their physical activities. Another possi- 

 bility is that of the effect of cold on protozoa in their relation to bacteria. 

 The intiuence of the increase of bacteria in frozen soils on fertility is unknown. 



Radio-activity and vegetation, G. Tkuffaut (Jardinaf/e, lOlJf, May; noted 

 in Gard. Chron., 3. ser., 55 iWU), No. U31, pp. 378, 379; Agr. News [Barha- 

 dos], 13 (1914), No. 318, p. 215). — In a series of experiments with leguminous 

 and other plants in soils containing radium bromid as the radio-active manure, 

 but also rich in nitrogen and other mineral fertilizers, a progressive decrease 

 of yield corresponded to a higher content of the radio-active substance. It ap- 

 peared in some cases, however, that as the nitrogen was used uj) in the soil 

 the later crops showed an increase thought to be due to the radio-active factor 

 under these conditions. 



In a second series of experiments, carried out with chi*ysanthemums in pots, 

 the relative values of different radio-active substances were investigated. It 

 was concluded that radio-active substances produce a definite effect on vege- 

 tation, the insoluble not less than the soluble forms, radio-active minerals 

 or oxids giving the best results; that black oxid of uranium is practicable, 

 giving good results at low cost; but that radio-active residues of commercial 

 manufactures may contain injurious quantities of such ix)isonous substances 

 as salts of barium or suli^huric acid. 



Experiments with spinach in the. field gave no well-marked results. 



A summer's record of evaporation and precipitation in Lancaster County, 

 Pennsylvania, .Caroline Rumbold {Plant World, 17 (1914), No. 7, pp. 213- 

 215). — The author gives detailed records of observations regarding rainfall and 

 evaporation in a chestnut orchard in eastern Pennsylvania, covering the time 

 during foliation, lasting about six months. These climatic conditions are con- 

 sidered as nearly the optimum for deciduous trees of the temperate zone, espe- 

 cially for the chestnut tree. 



Specialization in vegetation and in environment in California, W. A. 

 Cannon (Plant World, 17 (19 W, No. 8, pp. 223-237, figs. S).— The results of 

 this examination of the surface, climate, and flora of California may be sum- 

 marized in a genei'al statement that there exists a conformity or association 

 between the last mentioned and the other two, the flora being extremely diverse 

 and highly specialized, showing not only response by species but sometimes also 

 by individuals. No particular attempt has been made to trace a causal relation 

 between any special environment and response thereto. Relation often appears 

 to be more accidental than otherwise, as in case of the Big Trees. However, 

 some suggestions regarding relationships are made. 



On the density of the cell sap in some desert plants, W. A. Cannon (Plant 

 World, 17 (191.'i), No. 7, pp. 209-212).— A study was made of Opuntia discata. 



