376 SCIENCE PROGRESS 



stance, presumably an oxygenase, which possesses the property 

 of activating molecular oxygen when exposed to the air, 

 peroxidases being formed as a result of the reaction. When this 

 power is lost the seed is no longer capable of germinating. It 

 is suggested that this peroxidase reaction should be turned to 

 account in seed-testing laboratories for detecting non-viable 

 seed and for distinguishing between seed of high, medium, and 

 low vitality. 



On the basis of loss of food reserves due to respiration 

 Sherman (I.e.) has calculated the possible life-duration of fully 

 imbibed seeds of a species of Amaranthus. The theoretical 

 value, thus calculated, fell far short of the actual value, which 

 certainly exceeds thirty years. 



Longevity of air-dry seeds forms the subject of a paper 

 by F. A. Welton (" Longevity of Seeds," Ohio Agric. Exper. 

 Sta. Monthly Bull., vol. vi, Jan.-Feb. 1921, p. 18). Com- 

 mencing in 1908, samples of seeds of a number of common 

 economic crop-plants were collected each year and stored in 

 corked glass bottles in a room without artificial heat. Early 

 in 1922 the viability of all the samples was tested and the 

 results set out in tabular form. A very high percentage of 

 clover seeds germinated after ten years' storage under the 

 above conditions, whereas some of the grass seeds tested showed 

 no germination after two years' storage. Results of germina- 

 tion tests of a somewhat similar nature are recorded by H. B. 

 Sifton (" Longevity of Seeds of Cereals, Clovers, and Timothy," 

 Amer. Journ. Bot., vii, 1920, p. 223). 



A striking example of longevity of seeds in a fully imbibed 

 condition is provided by the recently published results of 

 Dr. Deal's seed viability experiment which was started in the 

 autumn of 1879 (H. T. Darlington, " Dr. W. J. Beal's Seed- 

 Viability Experiments," Amer. Journ. Bot., ix, 1922, p. 266). 

 Twenty lots of fifty freshly gathered seeds from each of twenty- 

 three different kinds of plants were collected with the idea of 

 testing their viability at different times in the future. Each 

 set of seeds was mixed with moderately moist sand taken 3 feet 

 below the surface at a spot where the land had never been 

 ploughed. The mixture of seeds and sand was placed in a 

 pint bottle, the bottle being filled and left uncorked. The 

 bottles were then placed in the soil 20 inches below the surface 

 with the mouth slanting downwards to prevent water accumulat- 

 ing about the seeds. The results now presented are for the 

 germination test which was made in the spring of 1920, i.e. 

 in the fortieth year of the experiment. After this long period 

 of dormancy the seeds of ten species germinated, the per- 

 centage of germination in the case of a species of Amaranthus 

 being as high as 66 per cent. 



