. Compte rendu du Congre?s international d'essais de semences. Discussions at the International Seed Testing Conference. Verhandlungen der Internationalen Konferenz fu?r Samenpru?fung a?/in Copenhague (Danemark), 10. VI. 1921. Seeds; Seeds. 67 top for taking up the blocks of ice during the night. Between the two chambers is placed the cooling cell which causes the required cold in the cupboard. The system described above has satisfied us that it is relatively simple to keep the temperature constant at about 10° Centigrade, and that great temperature fluctuations cannot take place. Now we c
. Compte rendu du Congre?s international d'essais de semences. Discussions at the International Seed Testing Conference. Verhandlungen der Internationalen Konferenz fu?r Samenpru?fung a?/in Copenhague (Danemark), 10. VI. 1921. Seeds; Seeds. 67 top for taking up the blocks of ice during the night. Between the two chambers is placed the cooling cell which causes the required cold in the cupboard. The system described above has satisfied us that it is relatively simple to keep the temperature constant at about 10° Centigrade, and that great temperature fluctuations cannot take place. Now we come to the discussion of the second principal group, that of the thoroughly ripe seeds. According to their reaction when germinating at a reduced temperature they can be divided into two sub-sections :— Firstly, seeds germinating better when subjected to an alternating, temperature than to a constantly low Q DQ DD ???? FlGtlBB 3. Secondly, seeds requiring a constant low temperature. Consulting the existing literature, we generally find suggested an alternation between 20° and 30° Centigrade. This is likewise used for many seeds at Wagehingeh because it really seems to us the best method for their germinating, for instance for the. seeds of Anethum graveblens, Agrostis stolonifera, Brassica oleracea and Rapa, Carum Carvi, Festuca pratensis, Phleum pratense, Raphanus sativus and other kinds. For 18 hours a temperature of 20° C. is maintained, which is raised during the remaining six. It appeared, however, to us, that instead of an upward alternation, a lower one is advantageous for various seeds, and that this alternation yields the best results when using Jacobsen's method. Consequently our method, " Copenhagen alternating," came into use with us, in which the seeds are brought to, and kept for four hours at,the temperature bf 25-28°C., by heating the apparatus, after which the warm water at 32° C. is quickly substituted by cold water, from the main tap,
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