24ft PJnjsiolof/ical P re-determination 



Reynolds-Green and Jackson (31 & 32) have also shown that 

 acidity leads to the liberation of enzymes, and we may recall here 

 Plate's (30) observation that the food-reserves of seeds treated with 

 concentrated sulphuric acid for a few hours were completely utilised in 

 10 days, as compared with 15 days in the case of untreated seeds, and 

 that the subsequent development of the plants from the treated seeds 

 was correspondingly more advanced. 



The work of Eckerson{i2) and Effront(i3) is also important in this 

 connection. Eckerson set out to determine the limiting factor in the 

 delayed germination of embryos of Crataegus mollis, which had previously 

 been shown by Davis and Rose(<i) to have a definite after-ripening period 

 independently of the presence of their carpels and testas. Eckerson's 

 results were not conclusive, but she demonstrated a slow increase in the 

 acidity of the hypocotyledonary region of the embryo during the after- 

 ripening period culminating in a sudden increase towards the end of 

 this period. This sudden increase in acidity was correlated with the 

 formation of enzymes and with germination. She also found that 

 treating the embryos with hydrochloric, butyric, or acetic acid shortened 

 the after-ripening period and hastened the appearance of enzymes. 



Effront {I.e.) working with barley, found that treatment with lactic 

 acid (2 gm. per litre) favoured germination and at the same time in- 

 creased the amount of diastase present in the grains. 



Conclusion. 



The main conclusion which appears to emerge from this brief review 

 is that the conditions operating during germination and the early 

 seedling stage of the life-cycle of the plant are of the utmost importance, 

 especially in the case of annuals and biennials, i.e. in the case of the 

 majority of economic crops. Conditions operating during germination 

 exercise a pre-determining influence upon subsequent growth and 

 directly affect the yield. In many cases the value of the effects obtained 

 are from the economic point of view out of all proportion to the cost of 

 the treatments used. 



The selection of vigorous seedlings is a common practice among 

 horticulturists. It is recognised that some sort of correlation exists 

 between the vigour of the seedling and that of the adult plant, and some 

 recent scientific work (Gregory, I.e.) has quantitatively established this 

 fact. But the proper deductions have not been made. The vigour of 

 the seedling may be due either to hereditary causes or to environmental 



