19171 FIELD CROPS. 827 



new races, or blotypes, vary about modes of their own, and are not permanently 

 modifiable. Such mutations may become appreciable only by statistical meth- 

 ods. The biotypes constituting ordinary bacterial cultures have arisen and per- 

 sisted as mutations. 



Nitrocultures and their commercial application, F. C. Habbison {Proc. 

 and Trans. Roy. Soc. Canada, S. ser., 9 (1915), Sect. IV, pp. 219-223). — The 

 author reviews the applications of the methods employed in experiments by 

 himself in connection with Barlow (E. S. R., 17, p. 9-50; 19, p. .528), and gives 

 in tabular form the results obtained in later tests by himself. He states that 

 the best growths were found among those obtained from the alsike culture on 

 saccharose, those from vetch culture on dextrin dipotassium phosphate, and 

 those from alfalfa, soy bean, and red clover culture on wood ash agar. Com- 

 binations were also tried, and for the last two years 1 per cent saccharose and 

 i per cent mannite have given good results. 



The composition of the media and the mode of preparation of the cultures for 

 distribution are described in some detail. 



FIELD CROPS. 



Contributions to agronomic terminology, II-IV, C. R. Ball and G. V. 

 Pepee (Jour. Amer. Soc. Agron., 8 (1916), Nos. S, pp. 197-204; 4, pp. 228-2S7 ; 

 5, pp. S10S15). — The glossary of agronomic terms previously noted (E. S. R., 

 35, p. 30) is continued. Part 2 defines 14 terras relating to plants, 10 to roots, 

 24 to shoots and buds, 26 to stems and branches, 29 to leaves, and 7 to epidermal 

 appendages ; part 3, 31 terms relating to Inflorescence, 74 to flowers, and 80 to 

 fruits and seeds ; and part 4, terms denoting pubescence, protuberances and in- 

 flations, excretions, punctations, and perforations. 



Relative precision of formulas for calculating normal plat yields, W. W. 

 Stockbekgee (Jour. Amer. Soc. Agron., 8 (1916), No. S, pp. 167-175). — This 

 paper discusses the precision of certain fornmlas commonly used for calculat- 

 ing normal plat yields. The methods are compared in field experiments with 

 hops, including fertilizer tests and variations in cultural methods. 



The normal yields for the plats varied widely according to the methods of 

 computation, the values in some cases differing from the actual yield by 40 per 

 cent. The errors introduced by the use of the formulas discussed may be 

 remedied in part by correcting for imperfect stand and by replication. Cor- 

 recting to full stand does not always result in increased precision. Replication 

 brings about a very marked reduction in variability, although with only five 

 replications the error is still relatively large. 



The root systems of agricultural plants, E. C. Miller (Jour. Amer. Soc. 

 Agron., 8 (1916), No. 3. pp. 129-15^). — This is a review of the literature on 

 the root systems of agricultural plants gathered by the author in his studies 

 of the roots of corn and sorghum (E. S. R., 35, p. 437). The review includes 

 (1) the extent of root systems, including methods for their isolation, (2) the 

 relation of the weight of roots to the aerial portion of the plant, and (3) the 

 influence of moisture, fertilizers, and oxygen on root growth and development. 

 A number of tables are given which, for the most part, have been abstracted 

 and rearranged, and many new calculations made in order to bring out the 

 most important facts. Sixty-four articles are reviewed and listed in the bibli- 

 ography at the end of the paper. 



[Work with field crops in 1916] (Wisconsin Sta. Bui. 275 (1917), pp. 24-34, 

 figs. 6). — A further study by E. J. Delwiche of the problem of controlling lodg- 

 ing of oats has given results similar to those previously noted (E. S. R., 35, 



