LIFE SPAN OF SEEDS 51 



sade cells had been eaten away by bacteria and fungi during the long 

 period in the soil. No doubt Ohga recovered only a small remnant of the 

 seeds originally buried. During the centuries the bacteria and fungi had 

 eaten the coats of most of them down to the "light line," the seeds had 

 swollen and germinated, and the seedlings were killed due to deep burial. 

 Many leguminous seeds are hard-coated, and no doubt many of them 

 remain alive in the soil for years because of this fact. Goss ^'^ found seeds 

 of several species of clovers viable after 20 years of burial. Allers ^ claims 

 that hard yellow lupine seeds lay in the soil 40 years unswoUen and fully 

 viable. 



Nobbe found that some seeds of various species of Papilionaceae, Mimo- 

 saceae, Cannaceae, and Ranunculacae remain hard and viable after being 

 soaked in water for years. Different crops of seeds, red clover from vari- 

 ous parts of Europe, varied greatly in percentage of seeds remaining hard 

 after 10 days' soaking at room temperature as well as in percentage remain- 

 ing hard after 12 years of soaking; one sample had 5.33 per cent still hard 

 after 12 years in water and a sample of very small seeds gave 53.33 per 

 cent ■'^ hard after 37 years of soaking. After 9 years in water, ''^ white 

 sweet clover had 48.93 per cent hard, Vicia cracca 43.36 per cent, Labur- 

 num vulgare 94.5 per cent. Two samples of black locust showed 18.5 per 

 cent and 5.5 per cent hard after 153^ years of soaking. Davis ^i found 

 that some velvet-leaf {Ahutilon Theophrasti) seeds remained hard after 

 20 years in water. Kondo **^ found some seeds of Astragalus sinicus still 

 hard and alive after soaking in water for 21 years and ^- 5.50 per cent of 

 black locust seeds were hard and alive after soaking 14 years. Rees ^'•' 

 found that seeds of Alhizzia lophantha that had been in the soil at least 

 23 years were still hard and viable. The conditions in the soil with varia- 

 tions in temperature, moisture supply, and presence of organisms would 

 probably decrease the resistance to swelling. Yet it is likely that very 

 hard leguminous seeds such as palo verde," Kentucky coffee tree,^* and 

 certain Albizzias, Acacias, and Cassias may lie in the soil under favorable 

 conditions hard and viable for as long periods as the East Indian lotus 

 seeds. 



The only chance in the main for leguminous seeds to remain in the soil 

 alive for a long time is their failure to swell. Once they swell, the coats in 

 most species split and swell up into massive gelatinous tissue very subject 

 to attack by pectin bacteria ^- and the embryos are left unprotected and 

 subject also to bacterial attack unless good germination conditions pre- 

 vail. Bier '' indicates that some yellow lupine seeds bear substances that 

 offer considerable anti-bacterial action. The same thing is true of many 

 other hard seeds. The seeds that lie in the soil viable and swollen for 

 years have coats that do not rupture or otherwise decompose markedly. 

 They furnish good protection to the embryo and endosperm. 



In the next chapter, under types of dormancy, we shall have occasion to 

 discuss the anatomical, environmental, and genetical factors that deter- 



