94 AGRONOMY [BoT. Absts., Vol. VII, 



618. JuRiTZ, Chas. F. The prickly pear (Opuntia). Possibilities of its utilization. 

 South African Jour. Indust. 31:687-693. Idem. 32:803-814. 1920.— The possibility is dis- 

 cussed of utilizing the prickly pear as a useful fodder plant for stock and as an article of 

 human diet. It is also considered as a source of potash fertilizer, of sugar and vinegar, of 

 industrial alcohol, of oxalic acid, of oil, of a mucilaginous glaze, of sizing for textile fab- 

 rics, of fiber for paper making, of a dye or coloring matter, and as a basis for soap manu- 

 facture. From a practical standpoint not more than 7 or 8 of these seem to be deserving of 

 serious attention. — E. M. Doidge. 



619. Kalt, Bertram. Der Begriff "Originalsaatgut" und seine Anwendung bei der 

 Ziichtungsanerkennung. [The conception of "original seed" and its application to recognized 

 sorts.] Fiihlings Landw. Zeitung 68: 460-471. 1919. — A discussion of the inspection and con- 

 trol of pure seed production with a view to insuring the genuineness, purity, and quality of 

 the designated seed. An explanation of what the term "original seed" shall stand for, and 

 the use and meaning of such terms as "improved" and "pedigreed" as applied to particular 

 strains of seeds, and the organization and means through which such inspection and certifi- 

 cation may be carried out. — A. T. Wiancko. 



620. Keeble, Frederick. Intensive cultivation. Sci. Monthly 11:445-451. 1920. — 

 Extracts from an address at the Cardiff Meeting of the British A. A. S. — Skilled onion 

 growers average 5 tons to the acre. A chrysanthemum grower who turned his facilities from 

 these to onions averaged 17 tons. The average yield of potatoes is a little over 6 tons. The 

 army gardeners of France produced 14 tons to the acre. Consequently it may be accepted 

 as a fact that intensive cultivation would double crops. — L. Pace. 



621. Kelly, H. J. Agriculture at Nyngan. Agric. Gaz. New South Wales 31: 685-687. 

 1920. — Experiments have shown that wheat as a grain crop at Nyngan, 250 miles northwest 

 of Sydney, is unsafe, but that wheat for hay, and certain other fodder crops can be grown 

 after fallow, if light seeding is practiced. — L. R. Waldron. 



622. Killer, J. Die Knollenwachstumsintensitat, einer bisher wenig beachteter Faktor 

 in der Beurteilung der Kartoffelsorten. [The rate of tuber development, a heretofore little 

 noticed factor in judging the value of varieties of potatoes.] Fuhlings Landw. Zeitung 68: 

 426-430. 1919. — Varieties of potatoes of similar time of maturity differ materially in the rate 

 of growth at different periods. Some varieties make their most rapid growth early in the 

 season, some in midseason, and some late in the season. These observations lead to impor- 

 tant considerations regarding the utilization of plant-food in the soil, the influence of weather 

 conditions at different times in the season, effect of disease attacks, and relation to marketing, 

 and place the whole matter of potato culture in a different light than heretofore. With a 

 knowledge of the peculiarities of varieties in these respects, it is possible to regulate plant- 

 food supplies in the soil so as to be available when most needed, and to select varieties that 

 in their growth intensity at different periods fit in with the different weather conditions 

 usually prevailing at certain times in the particular locality. — A. T. Wiancho. 



623. Kiesselbach, T. A., and Ratcliff, J. A. Freezing injury of seed corn. Nebraska 

 Agric. Exp. Sta. Res. Bull. 16. 96 p. 22 fig. 1920.— The authors discuss various theories 

 advanced to explain the death of tissues by freezing. — Microscopic studies failed to dis- 

 close any rupturing of tissues or other cytological disturbances in corn embryos killed by 

 freezing. It is believed that freezing of a corn embryo produces a physical or chemical 

 change, aside from the withdrawing of water, in the protoplasmic and nuclear material of the 

 cell, so that death ensues. The change in color of the embryo as a result of freezing would 

 seem to indicate that a chemical change had taken place. — Control and field experiments 

 indicate that death from freezing is directly related to the moisture content of the kernel 

 and also to the duration of the exposure to cold. Seed corn maturing in a natural way 

 becomes cold resistant progressively as its moisture content diminishes. Seed corn mortality 

 increases progressively as the duration of the killing temperature is extended. — Extensive 



