Ifil6] HORTICULTUBE. 445 



A spraying manual (Fayetteville, Ark.: Univ. Ark. Ext. Div., 1916, pp. 16, 

 fiff. 1). — Tliis manual contains a monthly working calendar and directions for 

 spraying the more important insect diseases and pests of orchard and small 

 fruits, roses, and vegetables. Directions are also given for preparing various 

 spray mixtures. 



How to make hotbeds and cold frames (Harrishurg, Pa.: The Countryside 

 Presa, 1915, pp. 7Jf, figs. 21). — In this booklet popular directions are given for 

 the construction and management of hotbeds and cold frames, as well as the 

 smaller types of greenhouses. 



How to make a vegetable garden {Harrishurg, Pa.: The Countryside Press, 

 1915, pp. 13, figs. 14). — In addition to directions for planning and planting 

 vegetable gardens, specific directions are given for growing some of the more im- 

 portant vegetables, together with a monthly working calendar and planting 

 table. 



Some results in size inheritance, B. H. A. Gkoth (Neto Jersey Stas. Bui. 

 278 {1915). pp. 3-92, pis. 22). — In continuation of previous reports on heredity 

 and correlation of structural characters in tomatoes (E. S. R., 27, p. 742), this 

 bulletin gives the results and deductions from four generations of tomato 

 crosses. Some data are also given on crosses between varieties of Solanum 

 nigrum. 



The work done with tomatoes tlms far indicates that " the size of cotyledons 

 and first leaves is determined not only by sizes of the respective parental organs, 

 but also by other factors, as for example excess vigor in the Fi and the size 

 of seed in all generations. 



" The range and frequency distribution of size, shape, and number of all 

 characters studied in cotyledons, first leaves, large leaves, and fruits is of the 

 same nature, that is, wider than that of the Fi or either parent, but like that 

 of a continuous variation, showing in the great majority of cases only a single 

 mode, which agrees closely with the mode of the Fi unless excess vigor enters 

 as a factor. The dependence of the F2 frequency distribution on that of the Fi 

 is much greater than its dependence upon the frequency distributions of the 

 parents. Whether the parents are similar or dissimilar in respect to a certain 

 size character has very little influence upon the F2 range of sizes as to that 

 character. Instances are given of F2 frequency distributions which could not 

 have been caused by the Mendelian inheritance of any number of multiple 

 factors. 



" The size and shape of the Fi crosses between ± round fruits are the geo- 

 metric means of the parental sizes and shape. In the F, the variations in size 

 and shape are caused by the interaction of size and shape factors. When fruits 

 of different shape and size are crossed new shapes and sizes should be expected 

 to appear, some to breed true without the assumption of any multiple factors. 

 The constancy of unit factors of size and shape must be gravely doubted in 

 view of the influence which supposedly absent factors may have upon the 

 development of those present. 



" In the discussion the view is expressed that no size character can be due to 

 an absence of a size factor, that an organism can not carry for the same char- 

 acter more than one size factor in a homozygous state or two in a heterozygous 

 state, and that all other sizes appearing in crosses are due to changes in ex- 

 pression induced by the interaction of various factors for size, shape, or other 

 characters. An attempt is made to define a unit factor as a nervous stimulus 

 emanating from the nucleus as part of the centro-epigenetic system in the sense 

 of Rignano. It is suggested that the complexity of the chemical constitution 

 of the nuclear protoplasm, with its multiplicity of electron systems active at all 



