1919] AGRICULTURAL BOTANY. 29 



relation to interpret growth enlargement and incidental variations in the volume 

 and size of plant organs. It is also suggested that the differential action which 

 might follow a change in the quantity of a nitrogenous compound in the carbo- 

 hydrate body of protoplasts in special tracts, changing the imbibition capacity of 

 chromosomes, of spindles or cell plates, etc., may play an important part in 

 mitosis and cell division. 



Imbibition in biocolloids as affected by acidosis, alkalosis, and neutraliza- 

 tion, D. T. MacDougal (Carnegie Inst. Washington Year Book, 16 (1917), pp. 

 60-62). — Some systematic information as to the swelling of agar and gelatin 

 in water, acids, alkalis, and salts with regard to concentration of the reagents 

 has become available as the result of the work in the physics of simple colloids. 



The reactions of sections of living plants to similar solutions demonstrated 

 that protoplasm shows a characteristic behavior which may be simulated fairly 

 well by a mixture consisting of a base of an inert carbohydrate like agar and 

 albumin or its derivatives, which for convenience is designated as a biocolloid. 

 The swelling of dried sections of biocolloids gives data which can not be antici- 

 pated by a consideration of the known laws of imbibition of its components 

 separately, but it is confidently predicted that with wider evidence the general 

 behavior of a biocolloid may be foretold. Preliminary tests of imbibition by 

 biocolloids were made chiefly with a single concentration of the reagent, which 

 is taken to lie within the possibilities of conditions in the cell. 



The data obtained are tabulated, and show some of the more obvious features 

 of imbibition in a biocolloid as affected by conditions similar to those supposedly 

 prevalent in living plants. 



Imbibition of gelatin and agar gels in solutions of sucrose and dextrose, 

 E. E. Free (Carnegie Inst. Washington Year Book, 16 (1917), p. 66). — From a 

 comprehensive series of swelling tests made with sucrose and dextrose under 

 guarded conditions upon the swelling of biocolloids consisting of varying propor- 

 tions of agar and gelatin, it appears that for sugar solutions of less than 25 per 

 cent concentration the results do not differ from those for distilled water more 

 than is explainable by the accidental variation normal to the method when the 

 temperature is not precisely controlled. It is thought that neither sucrose nor 

 dextrose in concentrations under 25 per cent exercises any effect on the swelling 

 of gelatin-agar gels in water so important as that of acids or alkalis. No 

 specific effect of sugar was noted either on the swelling or imbibition capacity 

 of the gels. 



Gas interchange in Mesembryanthemum and other succulents, H. M. Rich- 

 ards (Carnegie Inst. Washington Year Book, 16 (1917), pp. 79, 80). — This is a 

 study of Mesembryanthemum, Dudleya, and Abronia under various conditions 

 of temperature and illumination as related to the acidity conditions of their 

 juices, most of the tests .being carried out in darkness, a number in diffuse 

 light or direct sunlight. The gas samples collected, over 200 in number, await 

 analysis by methods previously described (E. S. R., 35, p. 225). 



Desiccation and respiration in succulent plants, E. R. Long (Carnegie Inst. 

 Washington Year Book, 16 (1917), pp. 80-82). — Some results of earlier work 

 (E. S. R., 34, p. 430) are referred to as having shown that Echinocactus exposed 

 to air accumulates carbohydrate (a large portion of the increase being that of 

 soluble nonreducing sugar), and that during prolonged desiccation in diffuse light 

 oxidation of storage sugars keeps the relative dry weight of the plant tissue 

 at a constant figure. An attempt has been made by the author to combine these 

 effects in one plant in order to gain insight on the course of katabolism in carbo- 

 hydrate types and on the time element involved. 



An Echinocactus which had been loaded with carbohydrate, by being desiccated 

 in the open air for eight months, was placed in a ventilated dark chamber. It 



