1917] AGRICULTUBAL BOTANY. 27 



489). — Employing the potash test previously mentioned (E. S. R., 25, p. 222) for 

 determining gerralnability or Its absence, the author has experimented with 

 seeds of pepper cress in alcoholic or in saline solutions, in peti'oleum ether or 

 in ordinary ether, in moist air and in oxygenated water. He has detailed the 

 results of the several tests, with some references to observations previously 

 made by himself (E. S. R., 27, p. 330) and by Demoussy (E. S. R., 36, p. 29). 



Influence of the medium upon the orientation of secondary tei'restrial 

 roots, R. M. HoLMAN {Amer. Jovr. Bot., 3 iJ916), No. 8, pp. ^Ol-J^tJ,. figs. 3).— 

 The results arrived at by the study, previously noted (E. S. R., 35, p. 223; 36, 

 p. 129), of the primary roots of Vicia faba, Lupinus albus, and Pisum sativum 

 suggested the question as to whether or not the secondary roots of the.se species 

 show any relation between geotropic behavior and medium, such as exists in 

 primary roots. The author has carried out a .series of experiments, chiefly with 

 V. faba, in the course of which a striliing parallel was noted between the 

 behavior of primary roots and secondary roots of the first order, the media used 

 being air as neai'ly as possible saturated with water, uniformly moist sawdust, 

 and fine garden earth. The results are described in detail. 



The growth of forest tree roots, W. B. McDougall {Amer. Jour. Bot., 3 

 {1916), No. 7, pp. 384-392) .—A series of systematic observations, by means of 

 two methods described, on growing roots of Quercus alba, Tilia americana, 

 Carya laciniosa, and Acer saccharinum, are considered to show that the root 

 growth of forest trees corresponds to the warm period during which absorption 

 can go on. Any possible resting period in summer is deemed due to scarcity of 

 water and not to any inherent tendency of the plants toward periodicity in 

 growth. 



The toxicity of bog water, G. M. Rigg {Amer. Jour. Bot., 3 {1916), No. 8, 

 pp. 436, 437). — A brief statement is given regarding data obtained from studies 

 on waters taken from sphagnum bogs of the Puget Sound region and Alaska, 

 in relation to the injurious effect of such waters on certain plants (in this case 

 Tradescantia cuttings). The author considers these data to warrant the sug- 

 ge.stion that its content of colloidal matters is a large factor in the toxicity of 

 this water to certain plants. 



Experimental cultures of plants on the seashore, L. Daniel {Compt. Rend. 

 Acad. Set. [Paris], 163 {1916), No. 18, pp. ^85-^86).— During fifteen years of 

 experiments with various plants which had been taken from Rennes to Erquy 

 and there grown under exposure to spray and intermittent wetting with sea 

 water, no change of real significance or permanence occurred, so far as could 

 be detected. Any differences due to abundant or deficient water supply showed 

 a tendency to disappear quickly when the plants were returned to their former 

 environment. 



The establishment of varieties in Coleus by the selection of somatic varia- 

 tions, A. B. Stout {Carnegie Inst. Washington Pub. 218 {1915), pp. SO, pis. 4, 

 figs. 4). — The author reports that a single variety of Coleus propagated vegeta- 

 tively by cuttings in two main clones has shown gradual fluctuations and 

 sudden mutations, giving a total of 16 distinct and characteristically different 

 color patterns. The results indicate that slight variations, arising either as 

 sudden mutations or as gradual fluctuations, can perpetuate themselves. It is 

 claimed that bud variations in Coleus are common, give numerous different 

 types which may be vegetatively constant from the first or can be made so by 

 selection, show development of certain types more commonly than others, pro- 

 duce reversions to parental types, give development of different degi'ees of 

 variability among sister clones, and exhibit spontaneous changes in the funda- 

 mental color characters and in the cellular and tissue processes resulting In 

 color patterns. The results of the investigation indicate that in Coleus asexual 



