107 



shown to be so impermeable for water that clover seeds can lie from one to 

 two weeks in English sulfuric acid, and for years in water, without losing 

 the coloring matter which in itself would be soluble in water. In such cases 

 cnly mechanical treatment is of any use. Gaher and Klose^ mixed 

 the seeds of lucerne (alfalfa) and varieties of clover with fine sand and trod 

 for ten minutes on the bag containing the mixture. After this treatment, 

 13.4 per cent, of the seeds of the lucerne were found to be more capable of 

 swelling, 10.2 per cent, of the white clover and 37.8 per cent, of those of the 

 bird's-foot, without showing any especial injury. Nobbe cites examples- 

 of an unexpectedly long retention of the germinating power. 32 per 

 cent, of seeds of Pinus silvestris, gathered in 1869, after having been kept 

 5 years in closed glasses in an occupied room, still germinated, and after 7 

 }ears 12 per cent. With red clover seeds (Trifolium pratense), preserved 

 in the same way, 10.5 per cent, germinated after 12 years, peas (Pisum sati- 

 vum) 47.7 per cent, after 10 years, Spergula arvensis 20 per cent, after 12 

 3'ears, flax (Linum usitarissimum) 49 per cent, after 6 years and 3 per cent, 

 after 11 years. Out of 400 seeds of the locust (Rohinia Pseud-Acacia) after 

 ten days, longer than which the time for practical purpose does not last, 

 71 grains germinated ; at the end of the year, 55 grains ; in the next year 18 ; 

 in the following year 7 and, after 7 years, one seed ; all were kept contin- 

 uously in distilled water which was renewed periodically. From these ob- 

 servations it seems credible to us that many buried seeds, unimpaired in life- 

 power, survive for very long periods. Even in the locust seeds mentioned 

 above, the remainder, left ungerminated after seven years, w^as still perfectly 

 healthy. A slight injury to the seed shell resulted after a few hours in a 

 swelling up and also, as a rule, in rapid germination. 



Disturbances of the second phase of the process of germination, the 

 stage of chemical action converting the solid reserve substances into the 

 easily transpired constructive matter, are observed very frequently. The 

 fact that many hard seeds such as Crataegus, Rosa, Juglans, Prunus, lie un- 

 harmed for a year in the soil, is not to be confused with real disturbances. 

 The difficulty of swelling may partly be to blame here; — during the dry 

 time in summer the seeds again become dormant. On the other hand water 

 may have permeated them already and have given rise to the formation of 

 ferments, which lead to the mobilization of the reserve substances. But this 

 action of the ferment is in itself too slow, up to the beginning of the dry 

 summer period, to sufficiently nourish the embryo. In different individuals 

 and varieties of all species which germinate with difficulty, germination and 

 development is found the spring following autumn planting. This takes 

 place especially if the seeds are sown soon after harvesting and when possi- 

 ble with the entire fruit. "Stratification" has been proved still more effec- 

 tive, i. e. the placing of the seed in layers in vessels filled with sand for the 



1 Gaiter und Klose, Quellungsunfahigkeit von Kleesamen. Wiener landw. 

 Zeitschr. 1877, No. 17, cit. Jahresb. f. Agrikulturchemie, XX. Year, 1S77, p. 181. 



2 Dobner's Botanik fiJr Forstmanner, 4th Edition, revised by Aobbe, 1SS_. 

 p. 382. 



