AGRICULTURAL BOTANY. 533 



Other tilings being equal, the greatest gi'owth takes place during cloudy 

 weather. 



Other observations were made showhig the point below which there was no 

 elongation of the shoots and the growth of different species during 24 hour 

 periods. AVith cherries, peaches, pears, apples, and plums there was no elonga- 

 tion of the tissues 9 to 12 cm. below the tip of the shoot or below the third leaf. 

 At the second leaf or at a distance of 5 to 8 cm. from the tip of the shoot the 

 lower iuternode continued to elongate, but only about 5 to 10 mm. With grapes 

 the elongation below the second leaf amounted to 2 cm. The maximum growth 

 in 24 hours was 27 mm. for pears, approximately the same for apples, plums, 

 and cherries, '50 to 35 nun. for peaches, and 50 mm. for grapes. 



The relation between the form of leaves and their light requirement, 

 J. WiKSNER {Um^schau, 13 {1909), No. 7, p. 152; Rev. Gen. Sei., 20 (1909), 

 A'o. 11, p. -}Si). — In a memoir presented before the Vienna Academy of Sciences 

 the author discusses the relation which exists between the form of leaves and 

 their light requirements. 



He shows that by leaves being deeply cut or reduced to very narrow forms, 

 as in the case of the conifers, there is not only a great increase in the total leaf 

 surface but the reduction in form results in a decided diminution in the heat 

 from the sun's rays, and consequently favors the assimilatory action of the 

 leaves. 



As illustrating the resistance of narrow leaves to the heat of the sun, the 

 author cites the fact that a fragment of china-grass introduced under a lens 

 did not take fire for several minutes, while a fine-mesh tissue composed of about 

 400 cells of the same was almost immediately consumed. Under similar con- 

 ditions a bundle composed of 50 bast fibers took fire very quickly, while one 

 composed of only 25 did not begin to show the action of heat for 3 or 4 seconds 

 and a single bast cell remained unaffected for 4 minutes. 



Action of fertilizing' salts on plant enzyms, M. X. Sullivan {Jour. Biol. 

 Chem., 6 {1909), No. 2, p. XLIV; ahs. in Jour. Chan. Soc. [London], 96 {1909), 

 No. 560, II, p. 514)- — The author reports that potassium sulphate retards, while 

 the nitrate and mixtures of calcium hydrogen phosphate, sodium nitrate, and 

 potassium sulphate accelerate the oxidizing action of wheat roots. Mixtures of 

 the three salts in equal quantities increase, while the phosphate alone increases 

 and the sulphate alone diminishes, the activity of malt diastase. Sodium nitrate 

 had no action whatever. In his experiments plants were grown in a mixture 

 containing 100 parts per million of phosphoric acid, ammonia, and potassium 

 oxid, to which was added 200 mg. of starch paste. The roots converted the 

 starch into sugar. This activity was retarded by potassium sulphate and 

 calcium hydrogen phosphate but increased by the sodium nitrate or a mixture 

 of the three salts. 



The distribution of rennet in the various parts and tissues of plants, C. 

 Gkrber {Compt. Rend. Aead. Sci. [Paris], lJf8 {1909), No. 15, pp. 992-995; ahs. 

 in Jour. Chem. Soc. [London], 96 {1909), No. 560, II, p. 512). — The coagulating 

 l)ower of rennet obtained from various parts of plants has been determined with 

 reference to milk at a temperature of 42° C. 



The author found that in the green parts of the plants the rennet is roughly 

 proportional to the amount of chlorophyll. The reproductive apparatus contains 

 more rennet than the vegetative organs, and in the case of some Compositse the 

 styles contain more than the achene. Rennet appears to be distributed in the 

 plant in the same manner as the proteolytic ferment, and it is thought that 

 possil)ly both activities may bo due to one and the same enzym. In the root and 

 stalk of i)lants the bast alone contains any ai)preciable rennet activity, but 



