Aug. i 4 , 1916 Agricultural Value of Impermeable Seeds 769 



shows graphically the differences in this respect between four lots of red- 

 clover seed. Lot 2 was commercial seed, while the other lots were seed 

 which had been gathered and hulled by hand. While lot 3 was thoroughly 

 dry when gathered, lots 1 and 4 were gathered when the heads were 

 slightly green. 



The lower of each pair of lines indicates the progress of germination 

 of one lot of seed, the upper line the sum of percentages of germination 

 and of impermeable seeds, and the space between the two lines of the 

 pair the percentage of seeds which were impermeable at any given time. 



1. All of the seeds of lots 1 and 4 softened and practically all germi- 

 nated in, respectively, six months and two years. Yet only about 40 

 per cent of the impermeable seeds of lots 2 and 3 softened and germi- 

 nated in three years. 



2. Since the percentages of seeds of lots 1 and 4 which remained im- 

 permeable during the first 10 days were about the same as of lots 2 and 3, 

 it is evident that the original percentage of impermeable seeds bears no 

 relation to the rate at which these will soften or germinate. 



3. It should be emphasized that the differences in maturity of the 

 different lots of seed were not noticeable in the appearance of the seeds 

 and offered, therefore, no basis for estimating the percentages of im- 

 permeable seeds which the different lots contained or the rates at which 

 these impermeable seeds would soften. 



RATE AT WHICH IMPERMEABLE SEEDS BECOME PERMEABLE WHEN STORED IN MANILA 



ENVELOPES 



Hand-gathered, hand-hulled seeds were tested for germination and 

 impermeable seeds after being stored in manila envelopes for different 

 lengths of time. The first test of each lot was begun a few days after 

 the seeds were harvested, and the last test in some cases more than 4^ 

 years later. 



Table IV shows the calculated average percentages of the originally 

 impermeable seeds in some of these lots of seed which became permeable 

 in one month, one year, two years, three years, and four years. Loss of 

 permeability during storage is indicated by the minus ( — ) sign. 



1. The impermeable seeds of red clover, alsike clover, white clover, 

 and sweet clover became permeable very slowly in dry storage. The 

 red-clover seed changed more rapidly than the other kinds of clover 

 seed, but less than one-half of the impermeable seeds of this species 

 became permeable in four years. 



2. The percentages of impermeable seeds in lots of alsike-clover, white- 

 clover, and sweet-clover seed gathered in 191 2 increased slightly during 

 the first year and then remained about constant during the second year. 

 This initial increase is probably due to the seed's being tested the first 

 time before it was thoroughly dry. A similar increase occurred in a few 

 lots of red-clover and alfalfa seed. 



