67 



température-coefficient for a riae of 10° C, (Q,u) is thus found 



K K 



in this case by taking the relation ^^'^ , t^^" etc., instead of 



'^ 2 "^ 1 



Thus from the values of the presentation-time at dif- 

 férent températures found in this investigation we calcu- 

 late the follovving values t)f the température-coefficient 

 Q,o (cf. the table in § 9): 



K" _ '2' _ K, _ 16' _ K.„ _ 10'40' _ 



k;: - 1^40' - ^•^' k;; - 6' -^■^' k;„ - 4'2o* - ^•^' 



^^ =. ^' = 2.6, K-^ ^'20-^ K. ^ ^:20' ^ 



K,5 2'20' ' K,, l'40' K35 2'30' 



K,„ ^ l'40' 



K4, 260' 



zzz 0.0064. 



From thèse figures it is clear, that between 5° C. and 

 30° C. van 'tHoff's law applies to the geotropic presen- 

 tation-time. The température-coefficient Q,o is 2.G. 



At 0° C. the presentation-time is a good deal longer 

 then it should be according to van 't Hoffs law'): 

 probably this fact is connected with the cessation of 

 growth at that température. 



Above 30° C. the harmful influence of higher tempéra- 

 tures makes itself felt, so that there too the température- 

 coefficient does not folio w van 't Hoffs law. 



Speaking général! y we can say that the process, of 

 which the reaction-velocity is inversely proportional to 

 the presentation-time, follows van 't Hoffs law. For 



1) Dr. Kanltz pointcd ont in a letter, that this sudden change 

 in the température-coefficient at U" C. beconaes much noore slri- 

 king when calcnlating (^)i„ with the aid of the formula <^i,, = 

 10 10 (log K. - l"g K ,l ^y^ ,.^^ .^ ^j^.^ ^.^y ^^^^ ^ 2^,3 

 D — U 



