HISTORY AND BIBLIOGRAPHY 829 



seeds examined in 1908, with reference to adulteration, purity, 

 vitality, and the presence of Cuscuta. Vilke gives an account of 

 the presence of weed seeds found in Swedish seeds. J. Paczoski 

 notes the important weeds found in the Cherson Government. 

 A. Malzew reports on the more important weeds found in Russia; 

 black bindweed {Polygonum con/volvulus) and corn cockle {Agros- 

 temma githago) were common in wheat; oats had, in addition, wild 

 oats {Avena fatua, glabrata), and Neslia paniculata. In rye, the 

 black bindweed {Polygonum convolvulus), lamb's quarters {Gheno- 

 podium album), stickweed {Echinospermum lappula), and Neslia 

 pamculata were found. Lesage made a study upon the effect of 

 solutions of common salt and alcohol on the germination of garden 

 cress. 0. Munerati and T. V. Zapparoli of Italy have made a 

 study of weed seeds with hard coats. F. Johnson and R. Hensman 

 discuss the source of the alien flora of Ireland through weed im- 

 purities found in agricultural seed. A. J. Ewart made tests of 

 various grass and garden seeds with reference to the vitality of 

 seeds after a sea voyage. In a lengthy report on the prolonged 

 vitality of seeds it was found that quite a per cent of seeds ger- 

 minated after half a century. Rees made a study of hard seeds 

 with reference to the cuticular layer. This layer repelled the water, 

 and for this reason seeds retained their vitality. 



A recent paper by E. Lehmann on the temperature and light 

 relations and the germination of seeds, gives both an exhaustive 

 summary of the subject and a great deal of original matter. 



It is difiScult to say under what conditions seed will germinate. 

 Older investigators regarded light as having no definite action on 

 the germination of seeds. Crocker found that the structure of the 

 seed coats retarded germination in the case of Xanthium. Shull, 

 Crocker, and others found that oxygen hastened the process. In 

 a recent paper by E. Lehmann, attention is called to the action of 

 light and temperature on the germination of seeds, both of which 

 influence this action. The seeds of Whitlavia grandiflora indicated 

 that germination is retarded at higher temperatures but not at 

 lower. He designates some seeds, suoh as EpHohiwin roseum, E. hir- 

 sutum (Lehmann), and Vermvlca peregrina (Heinricher) as light 

 germinating seeds. Dark germinating seeds are represented by 

 Phlox drummondii. Lehmann found that 4 per cent germinate ia 

 light and 31 per cent in darkness. Maturity also influences ger- 

 mination of seed. When wheat is ripened at a lower temperature, 

 it requires a longer optimum temperature for germination than seed 



