424 PHYSIOLOGY [Bot. Absts. 



2889. MacDougal, D. T., and H. A. Spoehr. The origination of xerophytism. Plant 

 World 21: 245-249. 1918. — The authors discuss the direct effects of aridity on carbohydrate 

 metabolism, and conclude that both succulence and xerophytism are the result of a low water 

 supply in the cells, which induces more rapid transformations of the polysaccharids in one 

 direction or another. If this accelerated transformation is toward the pentosans or muci- 

 lages, succulence results. But if conversion is toward the anhydrous substances like cellulose 

 and other wall forming materials, xerophytism results. Changes may occur in both direc- 

 tions in the same plant, as in massive cacti, where the epidermal structures are xerophytic, 

 and the cortical regions succulent. — Chas. A. Shull. 



2890. Northrop, J. H., L. H. Ashe, and J. K. Senior. Biochemistry of Bacillus aceto- 

 ethylicum sp. nov. with reference to the formation of acetone. Jour. Biol. Chem. 39: 1-21. 

 1919. — An organism has been isolated and described which produces acetone and ethyl alco- 

 hol with smaller amounts of higher alcohols from starch or sugar. Optimum cultural conditions 

 have been determined and a semi-continuous method for carrying on the fermentation has 

 been described. Other workers have described several organisms as producing acetone and 

 at least two such organisms have been used on a commercial scale. — George B. Rigg. 



2891. Pickering, Spencer. The' action of one crop on another. Jour. Roy. Hortic. Soc. 

 43: 372-380. Fig. 54-59. 1919.— See Pot. Absts. 3, Entry 1773. 



2892. Popp, M. [Rev. of: Wagner El. J. V/asserstoffionenkonzentration und natiirliche 

 Immunitat der Pflanzen. (Hydrogen-ion concentration and natural immunity of plants.) 

 Centralbl. Bakt. II, 33:708-719. 1916.] Biedermann's Zentralbl. Agrikulturchem. 47:258- 

 259. 1918.— See Bot. Absts. 3, Entry 1668. 



GROWTH, DEVELOPMENT, REPRODUCTION 



2893. Blackman, V. H. The compound interest law and plant growth. Ann. Botany 

 33 : 353-360. 1919. — The growth of an annual plant, at least in its early stages, is reported as 

 following approximately the "compound interest law" — the weight of the seed, the efficiency 

 in the production of new material, and the period of growth corresponding to initial capital, 

 rate of interest, and period of time, respectively. From this, a simple equation is deduced, 

 capable of expressing the growth of active, annual plants. — R. W. Webb. 



2894. Mitra, M. Discussion of winter pruning vs. summer pruning. Better Fruit 13 1 : 

 8, 26. May, 1919— See Bot. Absts. 3, Entry 2350. 



2895. Simbo, Ippo. Hompo-san nisan no chuei: Kwansuru Kenkyu. Beitrage zur Kennt- 

 nis einiger einheimischen Pfianzengallen in Japan. [Studies on some plant-galls in Japan.] 

 [Title in Japanese and German, text in Japanese.] Bot. Mag. Tokyo 33: 1-12. 1919. — The 

 author describes the galls on Rhus javanica caused by insects (Schlechtendalia sp. and Nuru- 

 deopsis sp.). He considers their classification and their morphological and histological 

 characters as well as their development. Starch, sugar, fat, a trace of volatile oil, and con- 

 siderable quantities of tannin are found in the galls, while albumin and calcium oxalate can 

 be demonstrated only in early stages of their development. — K. Morita. 



2896. Stark, P. [Rev. of: Vochting, H. Die Polaritat der Gewachse. (Polarity of 

 plants.) Tubingen, 1918.] Zeitschr. Allg. Physiol. 18 2 : 29-30. 1919.— The reviewer points 

 out that this work is volume 2 of Vochting's investigations on the experimental anatomy and 

 pathology of plants and that it is his last work. Special attention is directed to the patho- 

 logical changes which occur in the anatomy of roots and shoots grown with abnormal orien- 

 tation. A statistical study of the cell length in various regions of the stem of normal plants 

 showed that the average cell length increased from year to year, at first rapidly, then more 

 slowly. In Salix fragilis the increase in the first 11 years was from 34.8 to 70.8 units. In the 

 next 56 years the value increased to 89.1 units. In horizontally placed or inverted twigs the 



