4 Phf/siolofflcal Fre-determination 



In the second category we have a large amount of experimental work 

 which has been undertaken with the object of obtaining a simple method 

 of sterilising seeds. In this work tests of the growth and yield of the 

 plants from treated seeds as compared with that of the controls from 

 untreated seeds have been carried out, but in considering the yields 

 obtained the authors have not distinguished between the specific 

 physiological effects of the heat-treatment and the effect of seed sterilisa- 

 tion. 



Finally we have a category into which fall experiments carried out 

 with the definite object of ascertaining the pre-determining efTect upon 

 growth and yield of exposing seeds to relatively high temperatures 

 (cf. >Sprengel(33); Ockel(25); Pietrusky(27); Krasan(2i); Velten(36): and 

 Wollny(i3&44)). The results obtained are contradictory, and no definite 

 conclusion can be drawn from them. 



The most striking of the earlier results appear to have been obtained 

 with flax by Pietrusky. A brief exposure of the air-dry seed to tempera- 

 tures ranging from 30° to 50° C. increased the quaHty and yield of the 

 fibre produced by the experimental plants. 



Wollny (43 &44) in the case of a number of cereals and other economic 

 crops reached the conclusion that dry heating the seed generally increased 

 the productivity of the plants produced. Some of the results obtained 

 by Wollny are summarised in the following tables (Tables III and IV) : 



Table III (after Wollny). 

 Experiments carried out in 1876. 



Kind of seed 

 White lupins 

 Peas 

 Flax 



Number 

 of seeds 



200 



200 



Percentage 

 Weight of the experimental loss in 



seeds weight during 



^ > the drying- 



on April 5th on April 30tli process 



82-49 gm, 

 68-23 



— 100 



80-07 gm. 



64-75 



96-95 



2-93 

 510 

 305 



Weight of the 



untreated 



seeds 



83-30 gm. 



67-80 



99-30 



Temperature 

 maintained 

 during the 



drying-process 



30°-35° C. 

 30°-35° C. 

 30°-35° C. 



Harvest Results. 



Kind of seed 



Lii[>in 



Peas 



Condition of seed sown 

 \ Dried at 30°-35° C. 

 ) Untreated 

 I Dried at 30°-35° ('. 

 I Untreated 



Percentage of 



l)lants at the 



harvest 



87 

 95 



91 



Yield from 100 plants 

 Seeds Straw 



371 gm. -106 gm. 



264 

 1381 

 1143 



347 

 1594 

 1410 



