640 EXPERIMENT STATION RECORD. 



plants may become turgesceiit and then dried without serious injury to 

 their vitality, but a few varieties are injured, and, in general, drying up 

 is fatal to the seedlings. The author agrees with Wollny that the par- 

 tial drying up of potato tubers materially increases the productivity of 

 plants grown from them. 



With regard to the influence of temperature on germination the 

 author maintains that perfectly dried seeds retain vitality under the 

 lowestatta i nable temperatures, but that even moderate freezing destroys 

 most of the turgescent seeds. With regard to tiie action of frost and 

 the freezing of plants he diflers entirely with the views advocated by 

 Sachs as to the influence of thawing, and adopts the results of Miiller- 

 Thurgau. The cell sap does not freeze, but the i^urer sap in the inter- 

 cellular spaces freezes ; plants that freeze at — 8° 0. do not perish until 

 exposed to — 20° C. The flrst effect of frost is to disorganize and 

 destroy the protoplasm of the cells, and the water thus set free exudes 

 from the cells to freeze. High temperatures are resisted by the plants 

 when they are in a dry state almost as well as low temperatures. Well- 

 dried seeds endure 50° 0. for a considerable time and 100° 0. for a short 

 time without loss of vitality. Turgescent plants are injured by heat, 

 because the chlorophyll pigment is decomposed by organic acids origi- 

 nating with the cellular fluids. The author substantiates Mliller- 

 Thurgau's discovery that potato tubers can be made to germinate soou 

 after maturing if they are ex[»osed for one or two months to a temper- 

 ature of 0° 0. or 2° C. in order to accumulate sugar; the potatoes 

 thereby become sweet, and the tubers will quickly germinate. This 

 sweetness is not due to freezing, as was formerly supposed. Such 

 sweetish potatoes may be rendered fit for use again by allowing them 

 to remain for some time in a warm place, as the brisk respiration 

 which takes place rapidly destroys the sugar. — C. abbe. 



Squirrel-tail grass, A. Nelson ( Wyoming Sta. Bui. 19, pp. 73-79, 

 Jigs. 3, pis. i). — Squirrel-tail grass [lloydeum jubatum) is commonly 

 known in Wyoming as foxtail. Alkali soils and wet places are most 

 infested with this weed. Scpiirrel-tail grass in heading forms long 

 barbed awns, and when the plant is mixed with other hay and animals 

 eat the mixture, these awns penetrate the gums, causing ulceration 

 of the jawbones and teeth. This occurs with cattle, sheep, and horses, 

 but most frequently with the latter, as they are most frequently fed on 

 hay. Care should be taken that the seed is not spread by the water 

 used in irrigating. Since the plant is an annual it may be subdued by 

 mowing the field at such intervals as to prevent its seeding for one 

 season. Plates showing the appearance of the plant and of the jaw- 

 bones of sheep injured by tlie barbs are given. 



Wild, or prickly; lettuce, J. C. Arthur {Indiana Sta. Bid. 52, pp. 

 8.^-113, pis. 4, 7nap 1). — During the past year inquiries relating to the 

 wild or prickly lettuce [Lactuca scariola.) were so numerous that a bulle- 

 tin of information was prepared giving a description of the plant, history 



