432 EXPERIMEKT STATION RECORD. [Vol. 43 



{1919), pp. 20.7-212). — An accuunt giving condensed details is presented of 

 injury done to dilfereut plants during tlie winter 1916-17 by tlae unaccus- 

 tomed conditions. 



Studies on frost injury to cereals and legumes, H. Fischer {JaJiresber. 

 Ver. Angeic. Bot., 13 {1915). No. 2, pp. 92-141)- — Extensive tabulations are 

 given of observations regarding effects of cold on different portions of cereals 

 and legumes, some of wliicli sustained remarlcably low temperatures. 



The significance of the manner of thawing for the preservation of 

 frozen plants, A. Akerman {Bot. Notiser, No. 2 (1919), pp. ^9-64, figs. 2; 

 No. 3 {1910), pp. 105-126). — The author concludes from the worlc here indicated 

 as done with different plants that the manner of thawing (rapid or slow) in 

 case of a frozen plant is not always without significance as regards the final 

 effect upon the life of the plant. INiany plants have been found that were 

 injured more by rapid thawing in lukewarm water than by slow thawing in 

 air. This holds, however, only when plants were subjected to moderate tem- 

 perature. If the plants were subjected to a certain low temperature (which 

 was found to differ for different plants and for the same plant in different 

 external conditions), the manner (rate) of thawing liad no significance for 

 that plant, for tlie reason that it already had been l^illed in freezing. Although 

 it appears that in case of plants frozen easily (near the freezing point of water) 

 rapid thawing may be as little harmful as slow tliawing, in general rapid 

 thawing must be regarded as distinctly tlie more injurious to the plant. A very 

 large amount of heat suddenly presented to a frozen part of a plant may be 

 significant in case of many plants investigated, but in case of less heat little 

 difference may be noted between rapid and slow thawing. 



Effect of seasonal conditions and soil treatment on bacteria and molds 

 in soilfj^. E. Brown and W. V. Halversen (loica Sta. Research Bui. 56 

 {1919), pp. 251-218, figs. 7). — A report is made on a study of tlie relative num- 

 bers of bacteria and molds in variously treated soils throughout the entire sea- 

 son. Samples were taken from six plats at 10 to 12-day intervals throughout 

 the year, the plats being located in the station series where soil investigations 

 were in progress. 



The organisms were grown on three different media and the numbers de- 

 veloping determined. It was found that the bacteria decreased in the late fall 

 with a drop in temperature until the soil became frozen, when the number of 

 bacteria rose with decreased temperatures and fell with higher temperatures 

 regardless of the moisture content. Upon the thawing of the soil, the number 

 of bacteria decreased. With increasing temperature, however, an increase in 

 bactei"ia occurred which reached the maximum on all the cultivated plats on 

 June 19, and on the continuous timothy plat on April 12. Two maximum 

 counts were observed during the year, February 12 and June 19, with inter- 

 vening minimum counts. 



It was found that during the summer and early fall the bacteria did not de- 

 velop parallel with either moisture or temperature, and during much of the 

 year other undetermined factors seemed to control bacterial development. The 

 treatment of the different plats is said to have led to some unexpected effects. 

 Applications of peat depressed the bacterial growth, while manure and clover 

 increased their number. The continuous timothy plat showed the largest 

 number of bacteria, t)ut this is tliought to have been due probably to the 

 topography of the plat. 



In regard to the molds, the numbers present in the soils were found to fluc- 

 tuate from one sampling to the next, but their number was apparently un- 

 affected by moisture, temperature, or soil treatment. There was apparently 

 no relation between the bacteria and the molds present in the soil. 



