24 



Blaauw also mentions this difflculty of the hypocotyls 

 growing out and he too was especially troubled by it in 

 spring, as he has told me himself. He thinks 'j that low 

 températures during the growing hâve an unfavourable 

 influence, but I cannot share his view on the ground of 

 m y own results. I am rather inclined to think, that high 

 températures facilitate the growth of the hypocotyls, 

 although straight plants are also obtainable at high 

 températures, as appeared in experiments, in which the 

 objects of experiment were kept at 35° C. during 24 hours. 

 The main cause, as it seems to me, is to be sought in 

 the want of fresh air, although I cannot adduce conclusive 

 experiments in support of this opinion. The method of 

 growing in doubly covered wooden boxes does not improve 

 the ventilation; moreover the atmosphère of the laboratory 

 is generally injurions (cf. § 7). Obviously it would hâve 

 been best to put the boxes, in which the oat-seedlings were 

 grown, out of doors in the fresh air, if a constant or nearly 

 constant température were not also necessary for growing. 

 In the beginning ail the objects were grown in the hothouse of 

 the institute, as this stands quite apart from the laboratory, 

 is lighted with electricity and is steam-heated. There I 

 was only troubled by the growing out of the hypocotyls, 

 when the température rose on sunny days and sometimes 

 at week-ends, as on Sundays the boxes were not aired. 

 After the 9^^ of March I had to leave the hothouse as it 

 was impossible to keep its température low enough on 

 sunny days. The only room I could use for further growing 

 was the dark room, where I also made my experiments. 

 This room, situated quite within the building remained 

 pretty well at the same température and an electric fan 

 enabled me to ventilate it the whole day at will. Never- 



1) A. H. B 1 a a u w, 1909. p. 12. 



