234 Physiological Pre-clete7inination 



In concluding this section dealing with the effect upon subsequent 

 growth and final yield of the total or partial removal of the initial 

 food-reserves of the plant, the main generalisation to be made on the 

 basis of the evidence reviewed is that the yield from the plant is approxi- 

 mately proportional to the initial amount of food-reserves available for 

 the embryo. 



{h) The effects of soaking seeds in water. 



The pre-determining effects of soaking seeds in water are often 

 pronounced. From the point of view of growth and yield, it appears 

 from the evidence we are about to review that these effects may be 

 good or bad, the result depending upon the external conditions during 

 the soaking treatment and upon its duration. How far this form of 

 treatment is properly included here under the head of treatments 

 affecting nutrition, is debatable. There is certainly a considerable 

 exosmosis of soluble food-reserves from seeds soaked in water, and on 

 the basis of such results as are described above, this should cause a 

 depression in growth and yield. On the other hand, owing to the fact 

 that actual growth is inhibited in the embryo under water, time is 

 allowed for a complete mobilisation of food-reserves in readiness for 

 very active growth as soon as the seed is sown, so that the early stages 

 of development may be unusually vigorous. The advantage of consider- 

 ing in this place the question of the pre-determining effects of soaking 

 seeds in water is that in dealing later with other seed treatments it 

 will be found that soaking the seed in water is necessarily bound up 

 w^ith many of these^. 



In the late seventies and early eighties of last century a group 

 of German workers, notably C. Kraus(25) and (2fi) and E. Wollny(42), 

 investigated very fully the effect upon subsequent growth and yield of 

 soaking seeds in water and obtained remarkable results. These authors 

 emphasised the importance of the conditions under which the soaking 

 was carried out, especially with regard to the relative amount of water 

 employed. Beneficial effects upon growth and yield were obtained when 

 the soaking of the seed was carried out with the least possible amount 



' In the Wolfryn proce.-,s of electrical treatment of seeds for the piirpcse of inereasinji 

 the yield, cereal and other seeds arc immersed in large tanks containing weak solutions of 

 NaCl or other salts through which a direct current is passed. It is stated by the inventor. 

 Ml H. E. Fry (see Letter to Agricultural Gazette, Lxxxvni. No. 2328, 1918. p. 138), that 

 in the course of the experimental tests, it was found that although the electrically treated 

 seeds gave the best results, the soaking treatment alone gave better results than no treat- 

 ment at all. 



