16 



be true in several preliminary experiments — that the 

 same resuit is obtained, when the stimulated plants are 

 placed vertically in the ordinary way. 



One hour's preliminary warming was taken as a mini- 

 mum, as on account of the construction of the thermostat, 

 the vessel with mould only acquired a constant tempéra- 

 ture after that time. 



At the same time it was verified by several thermo- 

 electrical déterminations, that this time of preliminary 

 warming was necessary and sufflcient. 



Nevertheless the présentation -time was also determined 

 after a longer period of preliminary warming with the 

 twofold object of ascertaining whether the influence of 

 the température made itself felt after a longer time only, 

 and of thus being able to take into account the time- 

 factor according to Bl a c k m a n. The columns for 1 

 hours', 2 hours', 4 hours' etc. preliminary warming in the 

 following tables, are therefore not strictly accurate, be- 

 cause the l^t hour is not strictly comparable to the 

 subséquent ones, since the time needed to arrive at 

 a given température is included in the first hour. That 

 time is of course shorter for the coleoptiles than for the 

 mould, but still it takes up a considérable part of the first 

 hour (cf. § 7). 



The first détermination was always of the presentation- 

 time after a stay of one hour at the température in ques- 

 tion. There upon a détermination followed after 4 hours' 

 (or sometimes 6 or 8 hours') preliminary warming. If 

 no altération of the présentation -time showed itself (as 

 was the case from 0° C— 25° C), no further déterminations 

 at that température were made ; if any altération was 

 seen, an endeavour was made to represent this altération 

 as fully as possible and déterminations were made after 



