Bouyoucos, Transpiration of Wheat Seedlings as Afifected etc. 5 



the same experiment. Special care was also taken to select seed- 

 lings of nearly uniform size and of the same vigor and health, as 

 possible. 



Experimental Results. 



As already stated the object of this line of investigation was 

 to determine the effect of different densities of a coraplete nutrient 

 Solution on the amount of water transpired by wheat seedlings per 

 Unit of dry matter produced. For this purpose the wheat plants 

 were grown in Solution, sand and soil cultures, containing various 

 densities of a füll nutrient Solution. The concentrations of this 

 Solution were seven in number, and ranged in strength from 0.0 

 to 4500 parts per million. The sand and soil cultures were used 

 first to duplicate the water cultures, and secondly, to see whether 

 the different densities of the Solution would affect the transpiration 

 in these cultures, in the same order or in the same magnitude as 

 in the water cultures. For the determination of these two points, 

 all the three different kinds of cultures were conducted at the 

 same time and under the same conditions, in order that their results 

 might be comparable. The sand and soil employed were of various 

 sized particles. The sand consisted of three different sizes, namely, 

 numbers, 1, 2 and 31/2- In other words, those which could pass 

 through a mesh of 1, 2 and 31/2 millimeters respectively, in diameter. 

 The soil consisted of a Dunkirk clay loam and of a Dunkii-k sandy 

 loam, the first being assumed to be the finer of the two. The 

 object of employing the sand and soil of different textures, was to 

 ascertain whether the size of particles exerted any influence upon 

 the density of the Solution in affecting the transpiration. To in- 

 vestigate this point, the cultures of the various sizes of sand, and 

 of the two soils, were carried on at the same time, and under the 

 same conditions. This part of the werk, however, will be reported 

 elsewhere. 



In Order to obtain definite and conclusive evidence on this 

 part of the investigation, the three different kinds of cultures were 

 repeated a large number of times. The Solution and sand cultures 

 were made five times each, and the soil cultures two times, 

 Inasmuch, however, as there were two different sizes of sand 

 in four out of the five cases, and two different kinds of soil in 

 both iustances, and since all received the same treatment, there 

 were reaUy nine sand and four soil cultures, respectively. The 

 Solution cultures conducted at the different times, contained in each 

 density, from three to five bottles with four plants in each receptacle. 

 The sand and soil cultures, also carried on at different periods, 

 contained in each density, from three to six baskets, with five to 

 six plants in each. The total number of plants in each concen- 

 tration in the diiferent cultures was, therefore, 96 in the five So- 

 lution cultures, 204 in the nine sand cultures and 80 in the four 

 soil cultui'es. 



