AGRICULTUEAL BOTANY. 137 



about the stem of the plant. This prevented evaporation from the surface, 

 and loss of weight was due to transpiration alone. 



The experiments were made with a considerable number of plants represent- 

 ing different families. The results are held to corroborate those of Wiesner, 

 who showed that transpiration is mainly effected by the red, blue, and violet 

 rays, while the yellow and green rays, which are optically the brightest, are 

 less able to effect transpiration, even if they do not hinder it. 



An atmograph, V/. L. Eikenberry {Bot. Gaz., 50 (1910), No. S, pp. 214-218, 

 figs. 4)-— A description is given of a form of apparatus designed to give a con- 

 tinous record showing the maxima and minima of evaporation and transpiration. 



Transpiration experiments with, the corn plant, T. A. Kiesselbach (Ne- 

 braska Sta. Rpt. 1909, pp. 125-139, figs. 2, dgms. 2).—K preliminary report is 

 given of experiments carried on with the corn plant to determine if possible 

 some practical means for reducing the amount of water that the plant must 

 absorb for normal growth. Forty plants in two series were grown, one of which 

 was grown in loam watered with well water, while the other was grown in 

 sand to which a complete nutrient solution was added. In the first series the 

 object was to determine the relation, if any, between transpiration and the 

 water content of the soil, while in the second a study was made of the relation 

 of soil fertility to the quantity of water transpired in producing a given dry 

 weight. A special form of pot was devised for growing the plants. 



It was found that nearly the same amount of water was transpired per gram 

 of dry weight in all saturations excei)t where only 20 per cent saturation was 

 maintained. Where the saturation of the soil varied from 40 to 98 per cent 

 the amount of water transpired per gram of dry matter varied from 224 to 

 242 grains. Where different strengths of nutrient solution were added to the 

 sand cultures, there was little difference in the amount of water used per 

 gram of dry weight. The strongest solution, 0.6 per cent, proved too strong 

 for normal development, and the amount of water required decreased slightly 

 with an increase in the strength of solution. 



Summarizing his Investigations, the author states that the quantity of water 

 consumed by similar corn plants in producing a given yield can not be materi- 

 ally affected by vai-ying the water content of the soil, other things being equal. 

 When the soil is dry, somewhat less water is used in producing a given dry 

 weight, but the yield is also decreased. 



There appeared to be little or no stomatic regulative control which would 

 adjust the rate of transpiration according to the external conditions. The 

 transpiration rate was found to vary with the changes in the several climatic 

 factors, relative humidity of the air being the chief among these. 



The transpiration curve is fairly parallel with the evaporation curve, and it 

 is possible that by knowing the rate of evaporation from a free water surface 

 the transpiration requirements may be approximately determined. 



The root development in the plants was found to be proportionately greater 

 in dry than in wet soil, so that plants which make their early growth in dry 

 soil may be expected to better withstand a later period of drought for the rea- 

 son that they would have a greater absorbing surface exposed to the soil 

 particles. 



Experiments on exosmosis in plants, P. Czapek (Bet: Deut. Bot. Gesell., 

 28 (1910), No. 5, pp. 159-169; abs. in Bot. Gaz., 50 (1910). No. 3, pp. 234, 

 235).— K preliminary report is made of investigations conducted to determine 

 the permeability of the plasma of plant cells to various substances, and the 

 critical concentration for securing permeability was determined. 



On the physiological processes in the sprouting of plants, H. MiJLLER and 

 O. ScHNEiDEB (Landw, Jahrb. Schweiz, 24 (1910), No. 4, pp. 235-243) .—The 



