292 W. Wendler: Chemische Physiologie 1917— 1919 [36 



la vitalitä dei s e m i di Trachycarpus excelsa II. Wen dt. (Bull. Soc. 

 Bot. Ital., 13. 9 — 11, Firenze, 1919.) — Während von nicht erwärmten Trachy- 

 carpus-Samea 86% zum Keimen gelangten, wurden sieben Gruppen zu je 

 100 Samen vorher durch 10' in Wasser von 40° bzw. 50° usw. um je 10° auf- 

 steigend bis zum Siedepunkt gehalten; andere acht Gruppen, auch zu je 

 100 Samen, wurden vorher ebenfalls 10' lang im Trockenkasten bei Tempera- 

 turen von 40° um je 10° ansteigend bis 110° gehalten. Letztere Gruppen er- 

 gaben bedeutend' mehr Vorteile als die in heißes Wasser getauchten: bei den 

 letzteren erlischt die Keimfähigkeit schon bei Temperaturen über 70°, während 

 von den Samen, welche eine Lufttemperatur von 110° ausgehalten hatten, 27% 

 noch zur Keimung gelangten. In beiden Fällen lag aber das Optimum bei 60°. 



So IIa. 

 248. Rose, R. C. After-ripening and germination o f 

 seeds of Tilia, Sambucus, and Rubus. (Bot, Gaz. 67, 1919, p. 281—308.) — 

 Summary: „General. — Air-dry seeds of Tilia americana, Sambucus canadensis, 

 and Rubus Idaeus do not germinate when placed on a moist substratum at room 

 temperature. In no case does water absorption seem to be the limiting factor. 

 Air-dry seeds planted in the soil over winter give low percentages of ger- 

 mination. — Tilia. — Seed coats are not the cause of dormancy, although they 

 may serve to lengthen the dormant period. A state of dormancy exists in the 

 endosperm or embryo, or both. — Seeds with coats removed after-ripen at 

 temperatures slightly above freezing. At 0° — 2° C seeds after-ripen, but do not 

 germinate. — At 4° — 6° C both after-ripening and germination take place. Seeds 

 after-ripened at 0° — 2° C germinate readily at 10° — 12° C, but very poorly at 

 room temperature. Once germination has begun growth proceeds best at 

 temperatures above 12° C. — As after-ripening progresses the hydrogen ion 

 concentration increases, as do also the water holding capacity and the oxidase 

 and catalase activities. — The greatest amount of free acid is present in the 

 germinating seeds. Autodigestion of pulverized seeds shows the greatest acid 

 increase in the after-ripened ungerminated seeds. This is probably due to 

 their high lipase activity. — Sambucus. — As high as 77 per cent of 

 germination was obtained by layering fresh seeds out of doors over winter. — 

 No satisfactory forcing agent has yet been found. A slight forcing effect of 

 several acids, bases, and salts has been observed. The best oi" these forcing 

 agents are nitrates and sulphates. — Although Sambucus seeds are probably 

 injured by drying, that is not the only factor to be considered, since freshly 

 gathered seeds with a moisture content of 22 per cent will not germinate when 

 placed on a moist substratum. — As yet it has been impossible to approximate 

 perfect germination, and much still remains to be learned concerning the 

 conditions necessary to reach it. — Rubus. — Dormancy is probably due to 

 the high breaking strength of the endoearp. Seeds treated with concentrated 

 sulphuric acid for 2 hours, then thoroughly washed, germinate readily on cotton, 

 filter paper, or quartz sand. — The Optimum temperature for germination lies 

 between 20° and 25° C. Seeds germinate equally well in light or darkness. 

 Naked seeds germinate poorly in soil. This may due to the; action of fungi, 

 bacteria, or the other causes as yet unknown. — As a practical method for 

 the germination of Rubus seeds, if one is not to resort to layering, the writer 

 suggests the following: The seeds should be removed from the pulp as com- 

 pletely as possible. If the berries are crushed and then thrown into water 

 most of the pulp can be floated off. The pulp still clinging to the seeds may 



