AGRICULTURAL BOTANY. 1025 



With tlie exception of tiie castor bean and unislinjelon, which developed 

 normally from the first, all the plants ceased to grow after the development of 

 a few leaves, and they remained in this state until the comini; of the rainy 

 season. With the advent of the rainy season all the plants responded in a 

 marke<l manner, excei>t the n;:sturtiums and teasel, which succumbed to the 

 evaporation in spite of the chansre in seasons. 



This is believed to indicate that the castor bean and melon were able to 

 absorb and transmit water to their foliajie faster than it was lost by transi)ira- 

 tion, and hence were able to carry on vigorous growth even during intense 

 drought. The nasturtiums and teasel failed to provide the excess of water 

 needed for growth even in the I'ainy season, and consequently perished. 



This experiment seems to indicate that, so far as the behavior of native desert 

 plants is concerned, the evaporating power of the air is an important factor in 

 controlling desert vegetation, aside from its indirect influence through the con- 

 ditions of soil moisture. 



The author figures and deseriiies a simple device for measuring evaporation. 



Evaporation and plant habitats, B. E. Livingston {Plant World, 11 (liJOS), 

 Xo. 1, pp. 1-9). — In continuation of previous- observations (see above) the author 

 calls attention to the fact that the evaporating power of the air appears to play 

 an important iiart in the determination of vegetation which can best succeed 

 in different but neighboring habitats of the same region. 



The experiments described were carried on in the vicinity of Tucson at 4 

 different elevations, and comparisons are drawn with tlie humidity and sun- 

 shine in other regions, from which it appears that the evaporating power of 

 the air furnishes a valuable criterion for the comparison of the conditions of 

 plant habitats, and it must be considered as being a controlling factor in the 

 determination of the plants occurring in any locality. 



The physiology of gum formation in the Amygdalaceag, W. Ruhland {Bcr. 

 Dent. Bot. GescU., ,.'J {1907), Xo. 6, pp. 30.2-315. figs. 3).— The author discusses 

 the various theories regarding the i)liysiology of the gum formation in plants 

 belonging to the stone fruits, particularly with reference to the gummosis of 

 those plants. 



The influence of grafting on plants containing hydrocyanic acid, L. 

 (iuiGNARD {Ann. Sci. Nat. Bot.. 9. scr., 6 {1907), No. 5-6, pp. 261-305, figs. 9; 

 Rev. Vit., 29 {190S), Nos. 735, pp. 61-68; 736, pp. 89-92; 738, pp. 11,5-152, figs. 

 5; 739, pp. 173-176, fig. 1; 7J,0,pp. 201-206, figs. 3; 741, pp. 229-231; abs. in 

 Compt. Rend. Aead. »SVf. [Paris], L',5 {1907), No. 27, pp. 1376-1380).— After 

 reviewing the published accounts of investigations by a number of authors on 

 the transfer <if alkaloids and other substances through the grafting of plants, 

 the author describes a series of experiments in which he grafted herbaceous 

 and perennial plants, using on common beans varieties of Pha.seoliis liniatus 

 that were rich in eyanogenetic glucosids, and sjjecies of Photinia and Coton- 

 easter, which were grafted ui)on quinces and hawthorns. 



The author found that whenever a plant containing eyanogenetic glucosids 

 is grafted ui)on one in which they are absent, or vice versa, there is no transfer 

 of the glucosid from graft to stock or from stock to graft. Among the Rosa- 

 cea' which seem to i)ossess the ability of forming these glucosids, the substances 

 will be transferred from stock to graft if the species are nearly related and con- 

 tain the same kind of glucosid; otherwise in the artificial symbiosis which is 

 established by grafting each si)ecies will retiiin its chemical proi)erties. 



The toxic effect of certain common salts of the soil on plants, Florence N. 

 Magowan {Bot. Gaz., 1,5 {1908), No. 1, pp. .',5-.'i9, fig. /).— -The author claims 

 that previous investigations in testing the toxic effect of sjiHs on plants have 

 either been made to test the limit of eudurance or the highest concentratiou 



