524 EXPEBIMENT STATION RECORD. [Vol.36 



the soil solution, balance between the soil solution components, forms of 

 nitrogen suitable for plants, the influence of quantity and quality of organic 

 matter, the proper basicity or acidity for a given plant, and the mutual in- 

 fluence of plants growing together. 



Growing plants in large containers under control conditions, R. C. Weight 

 (Jour. Amcr. Soc. Agron., 8 (1916), No. 2, pp. 113-116, pi. 1, figs. 2).— A descrip- 

 tion is given of an arrangement adapted to the growing of plants under 

 controlled and yet nearly natural conditions. It comprises a soil container 

 in bucket form, of heavy corrugated iron, 15 in. in diameter by 13 in. deep, 

 provided with drainage holes in the bottom and placed in a well made by 

 sinking terra cotta sewer tiles to within 2 in. of the surface of the gi'ound. 

 The cans are handled and weighed by means of a block and tackle and a 

 movable derrick. The data obtained are presented and discussed. The 

 temperature conditions in the cans are said to be kept fairly uniform and 

 to be practically those of natural soil. 



An apparatus for aerating culture solutions, P. Weatherwax {Proc. Ind. 

 Acad. Sci., 191^, pp. 157-160, fig. 1). — It is stated that the requirements incident 

 to experiments on various phases of plant physiology have led to the devel- 

 opment of an apparatus for the maintenance of a constant stream of air 

 for several days. This has proved to be very efficient for that purpose and 

 is now being used very successfully in the aeration of culture solutions. 

 The principle is that of the Sprengel mercury pump, the adaptations of 

 which are described. It is claimed that the economy and the wide range 

 of adjustment in this instrument are such as to allow its use for many other 

 purposes. 



Preliminary report on synthetic media, C. J. T. Doryland (Jour. Bad., 

 1 (1916), No. 2, pp. 135-152). — The term synthetic media is here used to mean 

 one containing only compounds of known composition and structure, including 

 both nutrient solutions and solid (synthetic) media formed by the precipita- 

 tion of an agglutinant from compounds of known composition and structure. 

 The author reports on an attempt, by the use of definite sources of energy and 

 nitrogen, to exclude all species but those which can use the particular source 

 employed in each case, thus limiting greatly the number of groups, also that 

 of individuals, present in any case. The schematic arrangement presented is 

 tentative and is limited to water-soluble compounds. Sixteen media have 

 been tested up to the present time, promising results having been obtained. 



The mechanism and conditions of growth, D. T. MacDougal (Man. N. Y. 

 Bat. Gard., 6 (1916), pp. 5-26, pi. 1, figs. 4). — The autlior presents results of 

 experimentation with the platyopuntias, thought to have an important bearing 

 on the main problems of growth, which requires building material of a highly 

 specific character, as exemplified in the author's results from studies with the 

 polymorphous plant Neobeckia (see p. 523). 



He states that joints or segments of the platyopuntias accomplisli nearly all 

 of their total enlargement during 60 to 100 days of the initial season in the 

 Tucson climate. Enlargement and secondary growth may take place as deter- 

 mined by branching and environic factors in the succeeding seasons, the changes 

 in volume of joints, including daily reversible alterations which are described, 

 amounting to 1/250 of the total length. The general features of the daily 

 growth record suggest that enlargement takes place after the smothering or 

 clogging acids have been broken down, and that it ceases when the supply 

 of building material is greatly reduced. 



The direct action of light on protoplasts and on body temperatures is to be 

 described in a later paper. 



