106 Varietäten, Descendenz, Hybriden. — Physiologie. 



have a greater reducing action upon soluble Prussian Blue than do 

 the extracts from deeply coloured varieties. Similarlj^ in Sweet Peas 

 the wings of the "Purple Invincible" and "Painted Lad}'" contain a 

 liraiting factor. The dominance of the lighter colours over the darker 

 is therefore due to the presence of a reducing factor. 



The author shows how the composition of different colour va- 

 rieties in Stocks and Sweet Peas may be represented in accordance 

 with these results. The original colour — producing factors C and R 

 of Bateson, Saunders and Punnett are represented in the new 

 scheme by the combination Aj P, A^ and their B factor by the 

 Peroxydase Pj. 



The peroxides X, and X, have not as yet been identified with 

 any organic substances. P, and A, have been directly identified by 

 means of the guiacum reactions. To P^ and Ai the tests have onty 

 been applied indirectly, and their existence is rather deduced from 

 analogy with P, and A^ than directl37^ denionstrated by means of 

 experiments. R. P. Gregory. 



Benecke. W., Ueber thermonastische Krümmungen der 

 Drosera-Tentakel. (Ztschr. f. Bot. I. 2. p. 107—121. 1909.) 



Im Gegensatz zu Correns kommt Verf. wieder auf die Darwin'- 

 sche Ansicht zurück, dass die Krümmung der D rose m -Tentakel in 

 warmem Wasser als thermonastische und nicht als hydronastische 

 Bewegung aufzufassen sei. Auch in warmer, feuchter Luft konnte 

 die Einkrümmung der Tentakeln beobachtet werden, obwohl „im 

 Luftbad die Reaktionszeit länger und der Schwellenwert der Tem- 

 peratur höher ist, als im Wasserbad." Das Minimum der Temperatur 

 für Dy. rotunäifoUa im Wasserbad ist 35'^, das Maximum 53°. Es 

 konnten Analogieen mit den von Correns bei Ranken beobach- 

 teten thermonastischen Krümmungen festgestellt v^erden. Dr. capensis 

 und Dr. binnata verhielten zieh ähnlich wie Dr. rotiiudifolia, dagegen 

 reagierte Dionaea auf Temperaturerhöhung nicht. 



K. Snell (Bonn.) 



Bergen, J. Y., The modifiability of transpiration in 

 young seedlings. (Bot. Gaz. XLVIII. p. 275— 282. fig. 1—4. 1909.) 



Seedlings of Cucutnis sativus, Ipomoea piirpurea, Liipiinis albus, 

 Mirabilis Jalapa, Nicotiana ,,SaMderae" , Oxalis corniciilata, Phaseolus 

 vulgaris, Salvia splendens and Sinapis alba were grown in well 

 watered earth, some under glass cases with air-tight joints and 

 others in the free air of a furnace-heated room. 



The results obtained from the transpiration measurements were: 



1. As a result of being grown in a highly humid atmosphere, 

 all the plants studied acquire a much greater than normal capacity 

 for transpiration in a moderately dry atmosphere. 



2. Different families and different genera of the same family 

 Vary greatly in their capacity to acquire by such culture a tendency 

 to extremely rapid transpiration. 



3. The transpiration ratios, for the same species, become notably 

 greater as the leaf becomes fully developed. 



4. The transpiration ratios are not necessarily greater when the 

 relative humidity of the air, during the period when transpiration is 

 measured, is very low, — than when it has a medium value. 



Trelease. 



