1020] HORTICULTURE. 535 



through a mutation in a coll of the growiiifr point so that one of the two factors 

 (SS) necessary for normal development was changed or 'fell away,' resulting 

 in a change in the genotical constitution." 



Dockajjo under the Federal wlieat grades, R. H. Rkown (f7. .S'. Dept. Agr., 

 Farnirrx' Bui. It IS {1H20). pp. 26", liofi. 10). — Dockage is descrihed, directions 

 for distinguisliing dnckage and foreign material other than dockage are given, 

 and the method of deti-niiining dockage is outlined in detail. Notes are given 

 also on test weight determinations on dockage-free wheat, grading dockage-free 

 samples, and on practical methods of handling dockage. The grade require- 

 rtients of the oflicial grain standards of the United States for wheat are given in 

 abridged form. 



Spraying; lawns with iron .sulphate to eradicate dandelions, M. T. Munn 

 (Xcw York State Sta. Bid. .',C,t] {J919), pp. 21-59, pis. 6, figs. 2; abr. cd., pp. 8, 

 fig. 1). — After reviewing earlier and contemporary investigations along this 

 line, the author reports a series of experiments from 1911 to 1919, including the 

 elTect of iron sulphate solution on the dandelion, other lawn weeds, grasses, and 

 clovers; a comparison of spraying with other methods of eradication; the toxic 

 action of iron sulphate; and the relation of weather conditions to the extent of 

 injury to grasses and weeds. A hihliography is appended. 



Seed from flowers castrated and bagged, castrated and not bagged, and un- 

 treated germinated 21. 56, and 71 per cent, respectively, indicating that parthe- 

 nogenesis occurs in T. officinale. Germination tests of dandelion seeds collected 

 from lawns showed that some of the seeds were matured sufficiently to germi- 

 nate as .soon as they began to leave the plant, the percentage of germination 

 increasing directly in proportion to the degree of maturity. 



The experiments demf>nstrate that dandelions may be eradicated from lawns, 

 at relatively slight expense and without material injury to the grass, by proper 

 spraying with an iron sulphate solution. From four to five applications are 

 required, first, just before the blooming pei-iod, one or two others following at 

 intervals of three or four week.s, and finally one or two in late summer or fall. 

 With proper management anil the application of grass seed and fertilizers in the 

 spring and fall of each year, spraying is necessary only about every third year 

 to keep a lawn practically free from dandelions. 



The cutting-out method of fighting dandelions is held to be laborious and 

 inelTective unless the greater part of the root is removed. Infrequent shallow 

 cutting is worse than none at all, as each cut off root promptly sends up one or 

 more new plants. 



HORTICULTURE. 



Breeding methods with Iiorticultural plants, ,T. W. Crow {Proc. Amer. 

 Soc. Hort. .Sf/., 16 {1919), pp. 19-2'/).— A contribution from the Ontario Agri- 

 cultural College. The author pre.'^ents a plant breeders' classification of im- 

 portant horticultural plant.s, with special reference to their method of repro- 

 duction, and di.scus^es tlu> principles of plant breeding as applied to the isola- 

 tion of mutations and recombinations of characters by cro.ssing. 



The term " isolation " is preferred to " selection " as better expre.ssing the 

 fundamental idea of most improvement work. It is pointed out that " selection " 

 as u.sed by Darwin implied a gradual change of a cumulative nature in each 

 succeeding generation. " Isolation," on the other hand, consists in the segrega- 

 tion of a type or line of heredity which Vas there all the time and which is only 

 brought to light through being segregated, as in the simple plant progeny test. 



Experiences in plant hybridization, H. Ness (Proc. Amer. Soc. Hort. Set., 

 16 (1919), pp. .52-60). — A contribution from the Texas Experiment Station, giv- 

 ing a resume of the author's investigations with the genera Kubus and Quercus. 



