VITALITY AND GEKMINATION OF SEEDS. 



211 



vitality of the seed produced by the prolonged action of 

 the absolute alcohol. This diminution of vitality is partly 

 due to the withdrawal of water and partly to a direct action 

 of the abs. alcohol. If the vitality of the seed be at a 

 low ebb, the alcohol may without actually penetrating the 

 integuments kill the seed, but if the vitality of the seed be 

 more pronounced the alcohol only exercises a depressing 

 influence upon the seed without actually killing it. This 

 diminished vitality is shown also in other ways. The 

 plants developed from seeds which have been in alcohol 

 for some time are not as tall as seedlings of the same age 

 developed from normal seeds. The cotyledons of normal 

 seedlings examined 10 days after germination has taken 

 place are found to be shrunken, yellow, and almost entirely 

 devoid of starch. The cotyledons of seedlings of the 

 same age, grown from seeds, which had been in alcohol 

 for three weeks were found to be large, swollen, and the 

 cells still containing plenty of starch grains. This is 

 partly due to the smaller size of the seedlings causing less 

 sugar to be absorbed and hence by allowing the latter to 

 accumulate in the tissue of the cotyledon hindering the 

 conversion of starch into sugar ; but it is also probably 

 partly due to a direct effect upon the fermentative activity 

 of the cotyledon. 



Since the vitality of a seed slowly diminishes as it grows 

 older, the effect of alcohol upon old seeds should be more 

 marked than upon younger seeds. This is well illustrated 

 by the following example : 





Absolute Alcohol 

 for 14 days. 



Normal Seeds. 



Peas, a few 

 mouths old. 



38 p.c. gerruiuated. 



95 p.c. germinated. 



3 year old 

 Peas. 



20 p.c. gerruiuated. 



73 p.c. germinated. 



Comparison percentage. 



40 p.c. 



27 p.c. 



