34 



THE PLANT WORLD 



H. 



f -v 



y^ 



f 



Fig. 1. Side View of Cone. 



Fig. 2. Basal View. 



seeds seem to bring it closer to tlie single leaf pinon (P. monophylla). 

 Although liaving a cone that was apparently little, if any, larger than the 

 ordinary cones of P. eduUs, the seeds are noticeably larger than those of 

 either this species or P. moiiophyUa. The present range of the pinon 

 pine covers the general locality where P. Lindgrenii was found, while the 

 single leaf pinon occurs more to the southward, yet the conditions during 

 Pliocene times may have been very different, and it is perhaps reasonable 

 to conjecture that this fossil species was the ancestor of P. monophyUa. 

 The figures illustrating this fossil species are reproduced from 

 Torreya by the courtesy of the editor of that journal. 



F. H. Knowlton. 



VITALITY OF SEEDS. 



The various experiments which have been lately conducted to ascer- 

 tain the effect of low temperatures upon the vitality of seeds have led 

 the author to investigate the effect of high temperatures upon the vitality 

 of a large number of seeds. The author has found that by drying seeds 

 in an oven at 65° to 75° C. for a day, and then at 90° C for a day, a great 

 many seeds will resist temperatures of 100° C. or even more. His 

 experiments were made with oats, rye grass, lettuce, sunflower, musk 

 flower, alfalfa, rape, California poppy, and poppy. Of these alfalfa 

 proved the most resistant. After an exposure of one hour to 110° C. and 

 then 1 hour to 121° C, 10 per cent of the seed germinated. Of other 

 seeds investigated the maximum temperature was for jDoppies 100° C. and 

 Schizopetalon Walkeri 105° C. The effect of exposure to the high temper- 

 ature was noticeable in all cases by the marked retardation of germina- 

 tion and by the extremely slow growth afterwards. The young plants 

 were weak and there seemed to be a loss of sensibility to geotropic 

 stimulus. Whether the plants would become normal or not was impos- 

 sible to say, as the conditions of the experiments were such that they 

 could not be grown to maturity. 



