1916] AGRICULTTJRAI. BOTANY. 331 



The morning rate of pwietration is greater than the afternoon rate in every 

 variety, but the hour of closing and the difference between maximum and 

 minimum opening differ with the variety. The author thinks that early closing 

 may be a profitable feature for the plant on account of a more economical 

 water balance. 



It is thought that, while many facts referred to periodicity may be explained 

 by the influence of light, temperature, and water content, there are still some 

 indications that after a prolonged period of darkness, the stomata tend to 

 open between 8 and 10 a. m., suggesting a tendency to periodicity. 



Observations on transpiration in sugar cane, J. Kuijpeb (Kuypee) {Arch. 

 Stiikerindiis. Nederland. Indie, 23 {1915), No. 45, pp. 1715-1733, pi. 1, fig. 1).-— 

 The work above reported was followed up with experiments on transpiration 

 in connection with the movements of the stomata and accompanying water loss 

 in sugar cane. Fresh stalks from six to nine months old were cut in the early 

 morning and placed in large bottles of water the surface of which was protected 

 from evaporation by a layer of oil. 



Abundant watering of the plants approximately doubled the amount of water 

 ordinarily transpired. The daily course of transpiration in different varieties 

 permits their arrangement into three groups, two of these attaining their 

 maxima respectively in early morning and at 11 o'clock, while those of the 

 third group show very small differences during the whole day. These differ- 

 ences in the utilization of available water are supposed to correspond to dif- 

 ferences in production and in resistance to drought. 



The daily loss of weight in one variety may double that in another. No 

 connection was established between transpiration rate and stomatal count of 

 leaf area. The maximum transpiration rate may be reached after the stomata 

 have begun to close, the rate of transpiration being in a measure independent of 

 stomatal behavior. Decrease or deprivation of light decreases transpiration. 

 The varietal differences in transpiration rate are thought to be important as 

 giving a new basis for the selection of canes for certain conditions of soil and 

 climate. 



Sap ascent, A. Maillefer {Bui. Soc. Vaud. Set. Nat., 5. ser., 50 {1914), No. 

 182, pp. 23-30). — It is thought that the amount of energy due to transpiration 

 of water evaporated, 15.1 kilogrammeters per kilogram, is insufficient to ac- 

 count for the observed facts of sap ascent, and that the living cells of the 

 wood must also play a part. 



A new theory of g'um flow, P. Sorauee {Ztschr. Pflanzenkrank., 25 {1915), 

 Nos. 2, pp. 71-84; S, pp. 134-154, figs. 5).— As a result of later studies (E. S. R., 

 27, p. 851) on the characters and behavior of cells and tissues in plants showing 

 gum flow, the author states that cultivated cherry trees belong to one of those 

 families which show considerable tendency to liquidation of certain portions of 

 their cell membranes due to reactions in various stored substances. This 

 tendency may often be noted in very young branch tips which may show cell 

 deterioration or gummosis. The conditions for gummosis here existing do not 

 necessarily result in its appearance, often having only symptomatic significance 

 and showing on examination merely more or less predisposition thereto. 



It appears that gummosis is primarily a condition of local plethora or a 

 storing of material which, on account of its richness in hydrolyzing enzyms, 

 can not develop into normal cell tissue. This condition manifests itself through 

 the coloration of certain cells and may be related in its development to weather 

 and nutritive conditions. 



Tlie artificial absorption of liquids by aerial parts of plants, C. Acqua 

 {Atti R. Accad. Lincei, Rend. CI. Sci. Fis., Mat. e Nat., 5. ser., 23 {191^), II, 

 No. 3, pp. 78-84). — Experiments are described leading to the conclusion that 



