II 



AGRICULTURAL BOTANY. 521 



author adds 17 siiecies which are recorded for the first time as containing a 

 cyanogenetic glncosid and the correlated enzym. . 



The influence of increased carbon dioxid content of the air on green /, 

 plants, H. FiscHEK (Jahresber. Ver. Angew. Bot., 11 (1913), pt. 1, pp. 1-8). — ''' 

 Studies with plants under glass subjected to an increased density of carbon 

 dioxid in the surrounding atmosphere are said to have produced, in almost all j 

 experiments, a notable increase in body growth by the plant; earlier and more * 

 abundant flowering and fruit in several cultivated species; fruit bearing by 

 ordinarily sterile hybrids; and greater resistance to parasites. 



The controlling influence of carbon dioxid in the maturation, dormancy, 

 and germination of seeds, I. F. Kidd {Proc. Roy. Soc. [London], Ser. B, 87 

 (191',), ^^0. B 597. pp. 408-421, fig. 1; abs. in Ganl. Chron., 3. ser., 56 {1914). 

 No. 1437, p. 34). — Experiments described are claimed to show that a 

 high content of carbon dioxid in the atmosphere retards or inhibits ger- 

 mination of seeds without injury thereto. The seeds may germinate at once 

 after i-emoval of the carbon dioxid, as in case of beans, cabbage, barley, peas, 

 and onions, or inhibition may continue indefinitely after removal of the inhibi- 

 tory carbon dioxid pressures. In some cases described it was terminated only by 

 complete drying and rewetting, or by removal of the testa. In such cases a 

 lowering of the permeability of the testa to gases is thought to occur, reducing 

 the admission of oxygen to the embryo and raising relatively the actual carbon 

 dioxid pressure in the embryo tissues. The production of carbon dioxid in 

 nature by decay of vegetable matter may, it is thought, play a part analogous 

 to that noted in these experiments. 



The growth of potatoes in a medium containing but little humidity and 

 very little light, H. Hua (Bui. 8oc. Bot. France, 60 (1913), No. 7, pp. 621- 

 623). — A description is given of the growth of three potato tubers left by 

 accident in a cave during the summer. Long, thin, etiolated shoots appeared 

 and from near their bases short branches were put out which bore tubers at 

 their extremities. No roots were observed to be formed, but in the absence of 

 absorption from the soil and assimilation through aerial organs about 50 tubers 

 were formed that weighed from 4 to 30 gms. each. The original weight of the 

 tubers was unknown. 



Decalcification of soils by smoke and effect thereof on plants, A. Wieler 

 {Jahresher. Ver. Angew. Bot., 10 {1912), pp. 58-74, figs. 6).— The effects of 

 smoke gases on the development of lupine, vetch, pine, oak, and beech are 

 shown and discussed. It is claimed that acids contained in the fumes may in- 

 jure forest trees, not alone directly, by their action on the foliage, but in- 

 directly, by forming soluble compounds with bases in the soil, thus permitting 

 valuable constituents to be carried away in the drainage. Calcium was found 

 to be notably deficient in soils examined which were unable to support forest 

 growth. 



The relative abundance of bacteria in forest soils and the influence of 

 soil characters on their development, A. Rauber (Forstio. CentbL, n. ser., 

 86 {1914), No. 4, pp. 195-208).— A study of bacterial flora of different soils at 

 varying depths in 1913 is said to show that the bacterial content of limy forest 

 soils in the upper layers is from ten to twenty times as high as in sandy soils, 

 and varies considerably with the depth. The relative smallness of the number 

 at or very near the surface is attributed to the development of humus acids 

 there, as noted by Migula (E. S. R., 29, p. 325). The importance of the influ- 

 ence of soil bacteria as regards decomposition varies greatly with local and 

 temporal circumstances. 



62591°— No. 6—14—3 



