132 EXPERIMENT STATION RECOBD. 



acceleration of growth, wliicli was more marked iu cases wliere the radio- 

 active powder was applied directly than where plants in tubes were exposed 

 thereto. 



Semipermeability of seed coats, C. A. Shull (Bot. Gaz., 56 {1913), No. 3, 

 pp. 169-199, figs. 9). — The author gives an account of investigations carried on 

 for two years regarding the character of the seed coat of Xanthium, with par- 

 ticular reference to the work of Becquerel (E. S. R., 19, p. 426), Brown (B. S. R., 

 18, p. 727), and Schroeder (E. S. E,., 25, p. 123), with conclusions substantially 

 as follows: 



The dry seed coats of Xanthium are impermeable to di*y alcohol, ether, chloro- 

 form, and acetone. Becquerel's results with coats of other seeds are confirmed. 

 No evidence of diffusion of oxygen through dry seed coats was obtained. 

 Selective semipermeability independent of living substance was established for 

 the seed coat of Xanthium (lists being given of substances admitted or ex- 

 cluded), which, it is said, may be removed and used as an osmotic membrane 

 of superior quality. The outer layer of the testa can not so function, and the 

 inner exceeds the middle layer in this respect, neither of these two being so 

 efficient alone as before their separation. The middle coat contains more tan- 

 nin than the inner, but the tannin does not exist in either as a continuous layer, 

 and semipermeability is not destroyed by treatment with solvents of tannin. 

 Semipermeability is said to have been demonstrated for the seed coats of plants 

 in six widely separated families, membranes of many plants showing this prop- 

 erty even when dead. It is said that the capillary and imbibition force of the 

 embryo of Xanthium when the seed is air dry is about 965 atmospheres, and 

 that an increase in the moisture of the embryo equal to 7 per cent of its air 

 dry weight reduces the internal forces by 590 atmospheres. It is stated that 

 the unusual intake of water noticed with some substances, especially with cer- 

 tain acids and alkalis, is due largely to the development of osmotically active 

 substances inside the semipermeable membrane: also that some evidence was 

 obtained unfavorable to Armstrong's hydrone theory of selective semipermea- 

 bility (E. S. R., 21, p. 126). 



A bibliography is appended. 



The influence of partial suppression of the reserve material in seeds upon 

 the anatomy of plants, M. Delassus (Conipt. Rend. Acad. Set. [Paris], 157 

 {1913), i\o. 3, pp. 228-230). — Reporting on an extension of studies already noted 

 (E. S. R., 26, p. 729), the author gives comparative results obtained, conclud- 

 ing that the effects of mutilation of cotyledons upon«the anatomical structure 

 of the young plants produced therefrom are marked, showing a retarded and 

 diminished growth expressed by lowered development of the tissues, especially 

 those concerned with support and protection. 



The function of grape leaves in relation to the clusters, A. Marescalchi 

 {Staz. Sper. Agr. Ital., 45 {1912), No. 12, pp. 9^0-9^//).— Experimentation is said 

 to have shown that grape clusters on defoliated shoots still form a considerable 

 amount of sugar, also that while quite a proportion of acid is noted there is a 

 deficiency as regards diffusible coloring matters. 



Some points on the floral development of red clover, J. N. Martin {Proc. 

 loioa Acad. Sci., 19 {1912), p. 129). — This is a brief discussion of the relative 

 rates of development of different parts of the flower of red clover, the resulting 

 inequalities observed, and the changing relations sustained. A more detailed 

 account is to appear later. 



Demonstrations of ectotrophic and endotrophic mycorrhiza, W. B. McDou- 

 GALL {Rpt. Mich. Acad. Sci., 14 {1912), p. 45). — An abstract is given of a report 

 on an investigation conducted to determine if possible the seasonal, physio- 

 logical, and ecological relations of mycorrhiza. 



