134 EXPEKIMENT STATION RECORD. 



uiiiie the freezing points of the solutions used. Different kinds of potatoes were 

 selected and placed in controlled conditions so that heat should be the only lim- 

 iting factor of the experiments. One collection was placed in an ice box where 

 a temperature of 2° C. was maintained, while another was kept at a tempera- 

 ture of 25°. 



At the beginning of the experiments the osmotic pressure of the different 

 potatoes was about 7 atmospheres. After 10 months in the ice box there devel- 

 oped a maximum osmotic pressure of 13 atmospheres. The lower temperature 

 favored metabolic activities resulting in the liberation of an acid, a catalyte, 

 and the fermentation of foods, stored in the form of starch and hemicellulose. 

 The change from colloids to crystalloids was accompanied by a rise in osmotic 

 pressure. 



The fermentation of the hemicellulose was indicated by a reduction in the 

 thickness in the cell walls of the potato tissue affected, and also by an increase 

 in the brittleness of the tissues. 



These studies are believed to be suggestive of the changes taking place in the 

 after-ripening of seeds, tubers, and bulbs, and to have a defluite relation to 

 several economic and scientific problems. 



Induced variations in the osmotic pressure and sodium chlorid content 

 of the leaves of nonhalophytes, F. J. Lewis {New PhytoL, 11 (1912), No. 7, 

 pp. 255-264; a&«- in Bot. Centbl., 122 (1913), No. 6, pp. 152, 153).— This is a 

 study of the effect of sea spray on leaves by immersion of those of several 

 species of plants in sea water and in salt solutions of corresponding strength. 



All the plants showed an increase of salt in different percentages, also of 

 osmotic pressure. In some the total increase in weight considerably exceeded 

 that due to the salt, indicating an absorption of water. Leaf cells of all plants 

 showed plasmolysis at first, but this disappeared in from 12 to 27 hours. The 

 cells were living at the end of the experiments. 



A study of the distribution of osmotic pressure in relation to water con- 

 duction in plants, E. Hannig (Ber. Deut. Bot. Gesell., 30 (1912), No. 4, pp. 

 194-204; ahs. in Bot. Centbl., 122 (1913), No. 4, p. 87).— This is a preliminary 

 statement in regard to the author's investigations on osmotic pressures in 64 

 plants, representing widely different conditions in regard to moistui'e. 



The results obtained are said to be somewhat at variance with the view as- 

 cribed to Fitting (E. S. R., 25, p. 430) that high osmotic pressure in leaves is 

 associated with equal pressure in the roots. The author found the osmotic 

 pressure in the roots to be less in all but a few cases and very much less in 

 some, as in Plautago, where it is just about one-half that in the leaves. 



Protoplasmic contractions resembling plasmolysis which are caused by 

 pure distilled water, W. J. V. Osterhout (Ahs. in Science, n. ser., 31 (1913), 

 No. 949, p. 379). — The author describes a form of plasmolysis, designated as 

 false plasmolysis, which is caused in the root tips of Zostera marina when placed 

 in distilled water. This condition resembles greatly that of true plasmolysis 

 produced by hypertonic sea water or hypertonic sugar solutions. 



A cheAical and physiological study of after-ripening of the Rosacese, 

 Sophia Eckerson (Abs. in Science, n. ser., 37 (1913), No. 949, pp. 378, 379). — 

 The author states that the hawthorn is one of the few seeds in which there is 

 known to be a dormancy of the embryo and that a period of after-ripening is 

 necessary before germination is possible. The food stored in the embryo is said 

 to be a fatty oil, neither starch nor sugar being present. The reaction of the 

 cotyledons is acid, but that of the hypocotyl is slightly basic. 



During the period of after-ripening a series of metabolic changes take place 

 in the embryo. The initial change seems to be an increase of acidity correlated 

 with an increase in water-holding power and an increase in the activity of 



