AGRICTTLTURAL BOTANY. 727 



sorios and a reddoiiinj; factor, wliieh in all jtrobability is an oxidizing fonnont. 

 I'ink, piirplish-rcd, and jiurplc which arise from successive oxidation sta^'es of 

 the aromatic chroniojien are tlie more common forms of anthocyanin. Albinos 

 result from the absence of the chromoj^en or the peroxidase. The bluing enzyms 

 are said to depend on the presence of both these factors. 



An extensive bibliojjraphy of the literature of flower colorings is given. 



The demonstration of the fornaation of starch in leaves, Sophia Kckerson 

 (Bot. Gaz., J/S {1909), \o. ,f, />/>. ^,l',-228).—A qualitative demonstration in pho- 

 tosynthesis is reported, in which the time required for the disai)pearance of 

 accnijHilated starch and that required for its subsequent demonstrable forma- 

 tion is recorded. The results are tabulated, showing the time required in dark- 

 ness to empty the leaves of starch, the time in diffuse light to make enough 

 starch to show clearly detined figures with the iodin test, and the time required 

 to show sharply defined dark figures, together with the necessary interval 

 required for the iodin to produce its full effect. 



Of about 30 species of plants studied the best for showing the disaiipea ranee 

 and reapi)arence of starch were Pelargonium hortoru.in zoiialc, Fiich.sia xpcciosa, 

 t^cnccio mik-anloidcs, Imixitieiis .sidtani, and young plants of sunflower, castor 

 bean, common beans, maize, and pumpkins. 



In connection with these studies the effect of temperature on tlie amount of 

 starch was quite apparent. The o]itimum temperature for photosynthesis was 

 found to be abou"! 2C>-22° C. In some of the experiments less starch was found 

 at the end of hot afternoons than in the early morning. The explanation for 

 this phenomenon is that translocation from the leaf into the stem increases 

 with rising temperature more rapidly than photosynthesis. 



Utilization of nitrogen in air by plants, III, T. Jamikson {Agr. Reftearch 

 .l.v.s-or. l-Sco/.] Tii)t. 1907, pi). 9-75, pis. //). — This is a continuation of a previous 

 publication (E. S. R.. 19, p. 127), in which the author describes and offers 

 evidence to confirm his theory that atmospheric nitrogen is directly assimilated 

 by plants through certain specially developed trichomes, to which the name 

 "nitrogen assimilators " is given. 



Stimulation of storage tissues of higher plants hy zinc sulphate, Berenice 

 SiLBERBERG (BuL Toircy Bot. Club, 36 {1909), No. 9, pp. //g" EGO, figs. .)).— The 

 effect of zinc sulphate on the storage tissues of a number of plants was inves- 

 tigated. In weak solutions it bad a stimulating effect, while in stronger ones 

 it proved injurious. 



Nf)rmal solutions and fractional normal solutions were teste<l on a large 

 ■number of plants. It was found that beets, sweet potatoes, Ivohl-rabi, i)otatoes, 

 and salsify were the most satisfactory subjects of experimentation. The effect 

 of the chemical on the tissues and also on the respiration was investigated, 

 and zinc sulphate was found to have a stimulating effect upon the respiration 

 of storage tissues when used in sixteenth-normal solutions. Fourteenth-normal 

 solutions or any stronger than those were found to inhibit the respiration of 

 storage tissues of potatoes. 



The influence of chemicals in stimulating the ripening of fruits, A. E. 

 Vinson {Science, n. set:, 30 {1909), No. 77//, pp. GO.'i, GOo). — In continuation of 

 the author's studies on the ripening of dates (E. S. R., 20, p. (550), a preliminary 

 account is given of recent investigations in which it was found that the perfect 

 ripening of seedling dates could be effected in 3 days or less by subjecting the 

 fruit to the vapor of acetic acid for 12 or 15 hours. At the end of this time 

 the fruits have become transparent nearly to the seed and will then ripen 

 naturally without further tri-atment. The process, it is said, can be accelerated 

 by exposing them to th(> sunshine or by hejitiug for some hours to 45° C. It 

 is believed that this i)rocess will permit the shipjaug of green dates and ripening 

 th<'m al their destination, as bananas are now handled. 



