314 Bulletin 312 



there was a striking increase in germination over the check, due to the 

 treatment. It can therefore be said that, without doubt, the beneficial 

 effects of acid treatment of hard seed will still be manifest after drying 

 has taken place. Seed, then, which has been treated in quantity for 

 sowing, can be dried out after such treatment without decrease in its 

 germinative ability. 



Efeci of washing after treatment 



The question of method of treating seed with acid, or rather of removing 

 the acid after treatment, may now be taken up. Table 11 is introduced 

 here to show the injurious effects on germination of washing with water 

 for too long a period after acid treatment. Samples of some of the lots 

 reported on in previous tables were treated with concentrated sulfuric 

 acid for periods of i or 2 hours, and these were then washed in water for 

 2 hours and subsequently dried for 5 or 6 days. The germinations then 

 obtained are, on the average, quite poor, although there are individual 

 exceptions. The seed coat, being softened by the acid, seems to be 

 easily injured by the process of washing. It is evident from these tests 

 that washing should not be continued, after acid treatment, for a longer 

 time than is necessary to remove all acid from the seed, especially after 

 the acid treatment has been long continued. 



It may also be stated here that in the opinion of the writers it is seldom 

 necessary to continue the acid treatment of any kind of clover seed for 

 more than 30 minutes, and 15 minutes is often long enough. It seems that 

 different kinds of seed and different lots of the same kind vary somewhat 

 in their resistance to the action of acid, and for some lots a longer time 

 of treatment is necessary than for other lots. This is a question that 

 should be determined for different lots by individual tests. Usually, 

 however, 15 to 30 minutes treatment is sufficient, the higher limit for those 

 lots that have many hard seeds and the lower limit for those with few. 

 When the germination is good in the natural condition, the acid treatment 

 is of course unnecessary. 



WHITE, ALSIKE, AND JAPAN CLOVER SEED 



The action of concentrated sulfuric acid (sp. gr. 1.84) on the germina- 

 tion of the seed of several species of clover has been determined. The 

 results obtained with the seed of white, alsike, and Japan clovers are 

 given in Table 12. For the white and alsike clovers used, a treatment 

 of 15 minutes gave the best results. For the Japan clover, which was 

 undipped, a treatment of 60 minutes was better. The seed coats of the 

 white and alsike seeds were injured by 60-minute treatment and those 

 of the Japan seed by treatment for more than 60 minutes. The germina- 

 tion of the white clover seed was increased from 76 per cent in the check 



