63^2 JOTTKNAL OF THE ROYAL HORTTCULTURArj ROCTKTY. 



plants attacked, together with the results of inoculations of a largo 

 number of different potential hosts. The author announces the dis- 

 covery of a mycoplasma similar to those he has descrihed for the grain 

 rusts for this species as well. — F. J. G. 



Humus, The Determination of. By F. J. Alway, E. K. Files, 

 and E. M. Pinckney {U.S.A. Exp. Stn., Nebraska, Bull. 115; June 

 1910). — Samples of thirteen soils were subjected to treatment to 

 determine their percentage of humus — a term used here to denote only 

 the part of the organic matter dissolved by ammonia (a 4 per cent, 

 solution) after the lime and magnesia have been previously removed 

 by treatment with dilute hydrochloric acid (p. 9). The results obtained 

 by treating the same soil differed by 10 to 230 per cent., according 

 as the Hilgard or the " official " method was employed. The latter 

 is the one commonly accepted in America and England, though 

 the most important data concerning humus have been obtained by 

 Hilgard. The results of the determination of humus ash vary even 

 more than in the case of humus, the amount found by the " official " 

 method (Huston-McBride) being from 4 to 38 times as much as that 

 found by the Hilgard (p. 11). The writer regards the latter method as 

 entirely reliable and the former entirely unreliable. The humus 

 extract obtained by the Huston-McBride method, after being passed 

 through a properly prepared porcelain filter to remove the clay which 

 that method permits to become incorporated with it, gives results 

 which are concordant with those obtained by the Hilgard method (p. 5). 

 Ammonia solutions of different strengths w^ere not found to have 

 the same solvent power for humus. In reporting the humus the per 

 cent, of humus ash should also be given, as it serves as an indication 

 of the reliability of the humus determination. — A. P. 



Insect-Catchingr Machine. By F. C. Bishopp {Jour. Econ. 

 Entom., vol. iii., pt. iii. pp. 314-315; June 1910). — A large cage open 

 on one long side on wheels containing a powerful lamp to attract moths 

 is figured. It is drawn over the infested fields and Has proved effective 

 in capturing numbers of moths. — F. J. C. 



Insecticide Act of 1910 {Jour. Econ. Entom., vol. iii., pt. iii., 



pp. 275-282; June 1910). — An Act has been passed by Congress setting 

 a standard composition for Paris green and lead arsenate, and prohibit- ; 

 ing the manufacture or sale in the States or Alaska of any adulterated | 

 or misbranded " insecticides, Paris green, lead arsenates, or fungicides, | 

 or articles which enter into the composition of insecticides or fungi- i 

 cides. " This Act should do much to make the use of insecticides more j 

 reliable, since in using a standard article the user will know^ with what j 

 he is dealing. — F. J. C. ; 



Iris albo-purpurea colchestrense. Anon. {Gard., May 13, 1911, | 

 p. 226; coloured plate). — This Iris, a seedling from the late Max | 

 Leichtlin, differs from /. aU)0-purpurea (figured in Bot. Mag. and the 



