AGKICULTURAL BOTANY. 23 



In addition to the physical chissilication into hard and soft dates they may 

 also 1k' f,'roniKMl into i-ano and invert snt,'ar dates, the lines of the latter crossing 

 those of the foi'nier. as the Dej^let Norn- is a typical cane sugar date, yet decidedly 

 a soft (»ne. The .M'Kentichi Degla is a cane sugar date of the hard class. On 

 the other hand, Saffraia, a typical hard date, is also an invert sugar date, and 

 Ilalloua is a hard lint only a partial cane sugar date. 



Detailed studies were made of the variety Deglet Noor, a cane sugar date and 

 a .seedling invert su.gar variety. It was found that the Deglet Noor shows an 

 Inclination toward cane sugar even in early stages, but from this point on it gains 

 chiefly in cane sugar until ripeness is approached, wlieu invert sugar takes its 

 place. The amount of inversion seems to be intluenced by the temperature to 

 which the ripening date is subjected. The invert sugar date shows an increase 

 parallel to the increase in dry matter. Duriug the period of maximum ripeuiug, 

 vvben dry matter is accunuilating very rapidly, cane sugar appears in consider- 

 able quantities. This is attributed to the formation of cane sugar at a greater 

 rate than the invertase is capable of inverting it. Many varieties of dates have 

 been examined and cane sugar is found to accunmlate just before the softening 

 of the fruit. At this time the invertase is readily extracted by solvents. The 

 difference in behavior of the 2 classes of dates during ripening is believed to be 

 due to the presence or absence of invertase. 



The influence of tension on the formation of mechanical tissue in plants, 

 It. P. lIiBBARU (Bot. G(i.z., J,.i {lOIJl), Ao. G, iJi). 301-382). — The author couducted 

 a series, of experiments with sunflowers, beans, castor beans, cabbage, coleus, 

 fuchsia, and vinca. subjecting the plants to tension and coni])resslon to determine 

 the effect of these stimulants on the mechanical tissue. Contrary to the results 

 l>y other investigators, but slight effects were noticed. 



Of the stems tested for the increase of mechanical tissue under the intluence of 

 longitudinal pull, only that of vinca showed a response, and in this the increase 

 was not great. Pull in the direction of the longitudinal axis of the plant caused 

 a small increase in the tissue of the main and lateral roots of sunflowers and 

 castor beans. Compression tension brought small increases of the mechanical 

 tissue in the stems of fuchsia, vinca, and heliauthus, but coleus gave no response. 



Selection breeding of self -fertile plants, C. Fruwirth (Arch. Rassen u. 

 (icscU. Biol., /, ilUOl). Nos. i. iJiJ. l'i.J-170: 3, pp. 281-313).— \ttev describing 

 various methods of breeding agricultural plants, their variabilit.v and powers 

 of transmission of characters, the author reviews the results obtained I)y a 

 number of investigators in selection and breeding. This is followed with 

 detailed accounts of exjieriments conducted on the selection, breeding of peas, 

 barley, oats, etc. 



Concerning- the self -sterility of some flowers, L. .Jost (Bot. Ztg., 1. Abt., 65 

 >l!>in'), No. 5-6. pp. 11-111, pi. 1). — Studies were made of a number of species 

 of plants, among them Coriidulis aint, C. lulea, *s'rc«/c ccrculc. Liliuni bulhi- 

 frritiii. Uciiicrocallis flara, Citrdaininc pratensis, Ci/ti.'ius sj)., and Lupinitu albas, 

 to determine the causes of the sterility of the flowers to their own pollen. The 

 investigations included studies of jKilkn. structure of styles and stigmas, 

 growth of pollen tubes in artiflcial solutions, in styles, etc 



A list of titles to the more important literature of the subject is given. 



Notes on xenia, E. A. Bunyard (Report of the Third International Confer- 

 ence, n)(i6. on Genet iCK. London: Roi/. Jlort. .Sfoc, 1901, pp. 291-300).— The 

 author reports observations on xenia. or tlie influence of foreign pollen upon 

 the maternal structure, and gives an account of exi)eriments with maize, beans, 

 jieas, iieaches. apples, etc. So far as his experience goes, he says that the occur- 

 rciH (• (if .xenia as an intbicnce of the pericarp is very rare, and that considerably 



ir).T>— No. 1—07 — — ;; 



