AGRTCULTTTRAr. BOTANV. 225 



hirt timt its (juantity variod coiisidoral)]!,. 'J"lu' I'xact nature of tL*^ orjiaiiic 

 silica i-oiii[ioiiiul was not determined. 



The bacterial flora of the soil and its importance for agriculture, F. Weis 

 {Tidfiskr. Laiidbr. Plaiitcavl, 12 (l!>0o), pp. 130-179).— A coniprehensive discus- 

 sion of our jiresent knowledge of the subject. — f. w. woll. 



Relation of plant growth to root space, S. Kumakiri (Bill. Col. Agr. Tokijo 

 Imp. Inic, 7 (1907), No. 3, pp. .'i37-^39).—On account of the observed fact that 

 many plants yield smaller returns when grown in small pots than when grown 

 in large ones, the author conducted a series of experiments with spinach and 

 barley to determine the effect of the size of pots on plant production. The 

 same kind of soil was used in each instance, the smaller pots holding 2 kg., 

 while the larger ones were of 10 kg. capacity. 



The plants were measured and weighed, and an examination of the roots in 

 both cases revealed great differences, the roots in the small pots growing along 

 the wall of the pots more than in the case of the larger ones. In the hirge pots 

 the plants flowered and ripened earlier than in the smaller ones, and with barley 

 the total yield in the large pots was 4.8 times that of the small ones, while 

 with the spinach the yield in the large pots was 2.5 times that of the .^mall pots. 



The production of races of cultivated plants inured to drought. I, Ana- 

 tomical-physiological investigations, X. Kolkunov (Izv. Kiev. Politelc. Inst., 

 1905, p. 82; abs. in Zulu: Opuitii. Agron. (Russ. Jour. Expt. Landw.), 7 (1906), 

 No. 6, p. 709). — This article is a part of the extended investigation undertaken 

 by the author with the object of producing by selection races of cultivated 

 plants which, utilizing the soil humidity most economically, will endure drought. 



After a review of the literature concerning the piK)tection of plants against 

 excessive evaporation the author arrives at the conclusion that all the available 

 data are not sufHcient to explain why two races of wheat very similar in 

 anatomical structure may differ in the magnitude of their evaporation. By 

 means of careful measurements the author succeeded in establishing the fact 

 that varieties of wheat and other cereals with different xerophytic properties do 

 not differ from one another l)y the presence of special protecting tissues or the 

 arrangement of their tissues, but only by the magnitude of the anatomical ele- 

 ments of their leaves. Moreover, it was found that the change of the magnitude 

 of the stomata always goes parallel with the changes of the other elements, and 

 hence it is sufBcient to confine oneself to the measurement of the variations in 

 the magnitude of some one element. As such a fundamental measure, the 

 author accepts the length of the stomata. 



The author also takes up the question as to what determines the degree of the 

 xerophytic property of a plant — the development of its root system, as many in- 

 A'estigators believe, or the magnitude of its evaporation. On measuring the 

 magnitude of evaporation in plants with different xeroi)hytic properties, the 

 author c-oncludes that there is a complete correspondence between the xerophytic 

 properties of a plant and its evaporation. 



From these preliminary experiments it is clear that there must exist a clo.se 

 connection between the magnitude of evaporation and the size of the stomatji. 

 This conclusion is corroborated by a whole series of experiments and measure- 

 ments made of different varieties of wheat and other gramineous plants. It was 

 found that the larger the stomata the more humidity the plant evaporates and 

 tlie lower its xeroithytic capacity. Guided i>y these conclusions tbe autlior suc- 

 ceeded in obtaining by means of selection during 4 years a race of wheat witli 

 a greater xeroi)hytic capacity. — v. fiiieman. 



