158 



testa became slimy an(J shortly decomposition set in, affecting the cotyle- 

 dons, which hindered the development of the seedlings. The production of 

 these cracks is due to the increase in volume of the seeds, when soaked, to 

 more than loo per cent.^ This produces a pressure on the testa and dis- 

 tends it. making it porous. This porosity can lead with dr\ing even to 

 rupturing. Through these cracks in the testa, the embryo, when moistened 

 a second time, gets much more oxygen for the food-reserve already be- 

 ginning to decompose, and also large quantities of water are more quickly 

 absorbed. Further, the dissolved organic materials are transferred more 

 easily osmotically. These may act unfavorably on further development. 

 A testa slowly and equally distended, remaining uninjured, will there- 

 fore probably more completely utilize the reserve substances of the cotyle- 

 dons and perhaps indeed force the fluids into the tissue of the cotyledons and 

 the dissolved reserves into the embryo by the turgidity produced by soak- 

 ing. We cannot enter here more closely into the enzymes occurring in ger- 

 mination and their action, but refer in this connection to the works of 

 Newcombe- and Griiss''. 



From these experimental results it can be safely asserted that the use 

 of seeds, which have been soaked until germination has started and then 

 dried off, should be avoided. I am also of the opinion that soaked seed is 

 to be used sparingly every time especially in dry regions. In the first place, 

 in dry regions, the conditions already brought about artificially by drying 

 soaked seeds can be repeated most easily in nature by continued heat and 

 drought and act much more injuriously than if the seed, in such a condition, 

 lay ungerminated in the soil. In the second place the plants become ac- 

 customed from the beginning to an excessive water supply. The tissue be- 

 comes more porous, richer in water and, requiring more moisture, dries up 

 much earlier with the occurrence of great periods of drought than if the 

 plants had developed with a scanty sui)ply of water. The evaporation in the 

 former condition is greater than in the latter. On this account, growers 

 often follow the rule that for vegetable plants developing rapidly (cucum- 

 bers, beans and cabbages) watering must not be discontinued, if the plants 

 have had abundant water when young. I have often found that i)lants from 

 soaked seeds are less thrifty than plants grown from the same seed which 

 had not been soaked, but which depended upon the natural moisture of the 

 soil. 



Treatment of Tree Seed.s. 



If the germination of tree seeds is interrupted by drought, the results 

 are very disasterous. This is felt most in planting trees whose seeds retain 

 their germinative power only a short time. Nobbe* found that the seeds of 



1 Nobbe, Handbiu'li, d. 122 



- Newcombe, F. C, Cellulose-Enzymes. Annals of Botany 1899, No. 49; oil. 

 Bot. Jahresb. 1899, II, p. 179. 



3 Griis^ J., Beitrage zur Knzymologie. Berlin 1899. Festschr. f. Schwendener, 

 Ueber Zucker- und Stilrkebildunp: in Gerste und Malz, III u. IV. Wochenschr. f. 

 Brauerei 1897, 1898. 



* Dcibner-Nobbe, Botanik f. Forstmanner. 4th. Ed., 1882, p. 382. 



