Angewandte Botanik. 399 



them to withstand severe climatic conditions better than the com 

 plant {Zea mays). The present paper deals with the comparative 

 study of the root Systems and leaf areas of corn (varieiy Pride of 

 Saline) and of sorghum (varieties Blackhull kafir and Dwarf milo). 

 The root Systems of 33 plants were isolated and studied. It was 

 found that for a given stage of growih each plant possessed the 

 same number of primary roots and that the general extent of these 

 roots in both a horizontal and vertical direction was the same for 

 all three plants. The maximum depth of root penetration for mature 

 Dwarf milo, Blackhull kafir, and corn was found to be 6 feet for 

 both the years 1914 and 1915. It was found that Blackhull kafir 

 and Dwarf milo possessed approximately twice as many secondary 

 roots per unit of primary root as did the corn plant. This is true 

 not only for both years but also for all stages of the root Systems 

 examined. Both primary and secondary roots of the Sorghums were 

 found to be more fibrous than those of corn plant. The leaf area 

 of the corn plant at all stages of its growth is approximately twice 

 as great as that of the Dwarf milo and never less than 1.5 times 

 that of Blackhull kafir. 



It is apparent, therefore, that the Dwarf milo a^d Blackhull 

 kafir plants would have the advantage over the corn plant under 

 any climatic condition that would tend to bring about a loss of 

 water from these plants. The two sorghums have, in the first 

 place, as compared to the corn plant, only one-half the leaf surface 

 exposed for the evaporation of water; and in the second place, they 

 have a root system which, judging from the number of secondary 

 roots, would be twice as efficient in the absorption of water from 

 the soil. M. J. Sirks (Wageningen). 



Surface, F. M. and R. Pearl. A method of correcting for 

 soil heterogeneity in variety tests. (Journ. agr. Research 

 Washington. V. p. 1039-1050. 1916.) 



It is generally admitted, says the writers' summary, that field 

 trials, including variety tests, are often of very little value because 

 of the large number of uncontrollable factors. Nevertheless, field 

 trials are becoming more and more a necessity in many phases of 

 agricultural investigation. 



Within recent years a number of investigators have shown 

 that the experimental error in such trials can be greatly reduced 

 by the use of systeraatically repeated plots. Nevertheless, if the 

 number of repetitions is not large, certain experiments may still 

 be unduly influenced by irregularities in the field. It would there- 

 fore be desirable if some method could be devised b)^ which the 

 yields of individual plots could be corrected in such a waj^ as to 

 take account of these irregularities. 



Check plots have frequently been used for this purpose. But, 

 aside from the extra labor and expenses involved, the results from 

 check plots have been far from satisfactory in many cases. 



In the present paper a method is proposed for use in correcting 

 for diflferences in the soil of different plots. The method in its pre- 

 sent form is adapted for use only when the plots are arranged in 

 blocks in a special manner, as indicated by the writers in a figure. 

 The method of obtaining this correction factor is as follows: In the 

 first place the probable yield of each plot is obtained by the con- 

 tingency method. This „calculated" yield represents the most pro 



