Physiologie. 573 



Eckerson, S., On the demonstration of the formation of 

 starch in leaves. (Bot. Gaz. IIL. p. 224—228. S. 1909.) 



A method for the determination of the time required for the 

 disappearance of accumulated starch in darkness and the time in 

 light required for its subsequent demonstrable formation; — with 

 a consideration of the best plants for the purpose, effect of tempe- 

 rature, etc. Trelease. 



Fawcett, H. S., The viability of weed seeds under dif f erent 

 conditions of treatment, and a study of their dormant 

 periods. (Proc. Iowa Acad. Sei. XV. p. 25—45. 1908.) 



Tabulation of results obtained from ninety-two samples of weed 

 seeds, representing fifty-two different species. The general conclusion 

 drawn from the experiments were that most weed seeds with thick 

 seed coasts require a more or less extended period of rest after 

 maturity, that Mustard and Pepper Grass require little time for 

 rest, that vitality is weakened by drying and that germination is 

 increased by exposure to the natural periods for the best seed ger- 

 mination, — the fall and spring. Trelease. 



Gregory, L. H., Notes on the effect ofmechanial pressure 

 on the roots of Vicia Faba. (Bull. Torr. bot. Club. XXXVI. p. 

 457—462. fig. 1-4. S. 1909.) 



Pressure, varying from 650 — 2000 grams was applied from 12 

 to 24 hours and examination showed that this pressure had no 

 effect in the mitotic figure or division wall in the root cells of Vicia 

 Faba. The morphological changes taking place in the cells of the 

 compressed roots were noted and the conclusion drawn that not 

 even a maximum amount of pressure or an absolute change in 

 environment will entirely stop or effect the normal development of 

 the cells of V. Faba. Trelease. 



Harshberger, J. W., Action ofehemical Solutions on bud 



development: an experimental study of acclimatiza- 



tion. (Proc. Acad. Nat. Sei. Philadelphia. LXI. p. 57— 110. Mr. 1909.) 



A series of experiments extending over two years, with a large 



number of chemical Solutions, on a variety of shrub and tree buds 



obtained from various localities. It was found that it was impossible 



to disturb the natural sequence "of bud opening by the Stimulus 



imparted to the twig by the chemicals used. In every case where 



the plants responded, they followed the sequence already established 



among plants from the same locality; likewise the sequence between 



northern and southern grown twigs was preserved. The principle 



that response is not arrested until a poison has actually penetrated 



and killed the living cells, — thus putting a stop to the suctional 



activity and responsive power of the living cells, — was corroborated. 



Trelease. 



Harshberger, J. W., The directive influeneeof light on 

 the growth of forest plants. (Proc. Acad. nat. Sei. Philadel- 

 phia. LX. p. 449-451. pl. 24—25. Au. 1908.) 

 Account of observations made on the directive influence of 

 light upon the hay-scented fern {Dicksonia pilosiuscula) and the 

 hobble-bush (Viburnum lantanoides). Trelease. 



