F. KiDD AND C. West 17 



reached the conclusion that the effect of treating seeds with various 

 chemicals before sowing is no index of the action of these chemicals 

 when applied to the soil. Injury to the young plant may result when the 

 chemicals are applied to the soil although no injurious effect is shown 

 when the seeds are treated before germination with the same solution. 

 However, little can be said on this subject with certainty until it has 

 been determined whether the solute under consideration penetrates the 

 testa or not. • 



(6) Chemical Agents other than Acids, 

 (T) Copper Sulphate (= Bluestone). 



We have previously dealt with the effect of soaking seeds in water (18), 

 and have drawn attention to the distinction which must be made 

 between seeds sown wet (i.e. immediately after the soaking treatment) 

 and seeds sown after re-drying, with or without storage. It is necessary 

 to bear these points in mind when deahng with the effect of treating 

 seeds with chemical solutions in which they are immersed for various 

 periods. 



In 1904 Breal and GiustinianiiO) published the results of an investi- 

 gation on the effect of treating the seeds of various cereals with a solution 

 of copper sulphate. Unfortunately, although they appear to have been 

 aware of the distinction which must be made between the effect of 

 soaking and the effect of the solute alone, their results, whilst demon- 

 strating a considerable increase in yield as a result of the treatment they 

 employed, do not allow us to draw any critical conclusion as to how far 

 they are due to the soaking and how far they are due to any specific 

 action of the copper. 



Their line of thought appears to have been as follow^s : Seeds sown 

 after being allowed to take up moisture are found to give a greater yield, 

 but damp seeds are very susceptible to fungal attack. Copper sulphate, 

 however, has frequently been employed as a fungicide in seed-treatments. 

 Hence, can seeds be soaked in a solution of copper sulphate, not only 

 without injury, but with a result beneficial to yield? Further, might it 

 not be advantageous to make up the copper sulphate solution together 

 with 2-3 per cent, of starch, on the grounds that by so doing the escape 

 of soluble food-materials from the seed into the surrounding medium 

 during the period of soaking would probably be decreased^? They 



' We have not found any published evidence to the effect that starch does decrease 

 the exosmosis of soluble food-materials from the seed. 



Ann. Biol, vi 2 



