70 



Comparative tests were carried out last year with various flower 

 seeds. Four to six different germinating methods wore tried at the same 

 time. The 10 degrees method proved to be the best method for several 

 sorts, but for several others, on the contrary, it appeared tiseless. By 

 after-ripening these seeds for some months, and then repeating the 

 germination tests, we learned that it was not a question of insufftcient 

 after-ripening, but that it is a characteristic of some flower seeds to germi- 

 nate better at a lower temperature. Here can also be distinguished seeds 

 which prefer a constant low temperature of 10°, such as Chrysanthemum 

 oarinatmn. Delphinium ajacis, Eschscholtzia spp., Matthiola inoana, and 

 Nemophila, and seeds with which an alternating low temperature between 

 10 and 20 degrees gives the best results. To this last category belong, 

 e.g. : Clarkia elegans and pulchella, Lobelia erinus, Nigella damasoena, 

 Viola tricolor, etc. 



Ladies and gentlemen, I have come to the end of my paper, and will 

 conclude by giving a short smnmary of the results obtained: — 



Firstly. — An alternating method between 11 and 26° C. tested on a 

 Jacobsen incubator, placed in a northern room, gave, in comparison 

 with the ordinary alternating one between 20 and 30° C. and with 

 other methods, higher and more constant germination flgures for 

 various kinds of seeds ; 



Secondly. — ^A temperature of about 10 degrees Centigrade is a per- 

 fect one and nearly always sufficient to get the highest germination 

 results possible for Dutch-grown cereals (barley excepted) which 

 are not fully ripe, and for some other kinds of seed. 



It occurs but seldom, relatively, that the germination is delayed, 

 notwithstanding the low temperature apphed, but, where it d.oes 

 occur, an intensive desiccation at about 35° C. for 5 to 7 days always 

 proves sufficient (barley excepted) to cancel the phenomenon of 

 delayed germination. 



Thirdly. — ^A low temperature either constant at 10° C. or alterna- 

 ting between lO and 20° C. is most favourable for the germination of 

 various agricultioral, horticultural and flower seeds. By means of an 

 A.S. refrigerating machine, well insiflated thermostats can keep a 

 sufficiently constant temperature of 10 degrees Centigrade. 



ZUSAMMENFASSUNG. 



1. Bine intermittierende Methode zwischen 11 und 26° C. ausgefuhrt 

 auf einem Jacobsen Keimapparat, aufgestellt in einem gegen Norden 

 gelegenen Raum, ergibt, im Vergleich mit der iiblichen Intermittierung 

 zwischen 20 und 30° C. iind mit anderen Methoden verschiedener Samen- 

 sorten bessere und mehr konstante Keimresultate. 



2. Eine Temperatur von 10° C. ist ausgezeichnet und fast immer 

 hinreichend zum Erhalten der moglichst hohen Keimergebnisse fvir noch 

 nicht ganz nachgereifte niederlandische Getreidearten und fiir einige 

 andere Samensorten. 



Eine verzogerte Keimimg kommt bei dieser niedrigen Temperatur 

 verhaltnismassig nur selten vor ; in diesem letzten Falle war eine intensive' 

 Trocknung bei 35° C. wahrend 5 — 7 Tage immer geniigend (ausnahms- 

 weise bei Gerste) um eine normale Keimung zu Stande zu bringen. 



3. Eine niedrige Temperattir von entweder 10° C. konstant oder 

 intermittierend zwischen 10 und 20° C. hat sich als sehr giinstig fiir die 

 Keimung verschiedener landwirtschaftlichen-, Gartenbau- und Blumen- 

 samen erwiesen. Mittels einer A.S. Kiihhnaschine konnen richtig isoUerte 

 Keimthermostaten auf diese Temperatur gebracht und geniigend konstant 

 gehalten werden. 



t LITERATURE CITED. 



V 1. 1921. Harrington, O. F. 



Physiological problems in relation to the germination of seeds- 

 Proceedings Assn. Off. Seed Anal, of N. Am., p. 15. 



