60 FUNGI. [CH. Ill 



that leaves developed in shade on short twigs should be 

 employed. The cut leaves having been tested and found 

 to contain nitrate are placed with their stalks in water 

 and exposed to light. He describes an experiment in which 

 the leaves lost the greater part of the nitrate in four 

 or five days under these circumstances \ When a varie- 

 gated Elder is used for the experiment, the diminution of 

 nitrate takes place in the green, not in the chlorotic 

 parts. The importance of light was also shown in the 

 case of Taraxacum dens leonis, Aristolochia sipho' and some 

 other plants by observing that after some weeks of sunny 

 weather the sun-leaves gave no nitrate reaction while the 

 shade-leaves showed a moderate or even strong reaction. 

 Pelargonium zonale is also especially useful according to 

 Schimper, the nitrate reaction in this plant varies with 

 the weather : in bright sunny periods there is no reaction, 

 after dull weather it appears again. 



Section B. Nutrition of Fungi' and of Drosera. 



(80) Method. 



Make the following^ nutritive solution (N). 



Dextrose 5 to 10-0 grams 



Peptone 1 to 2-0 



Ammonium nitrate 1-0 



' loc. cit. p. 132. s loc. cit. p. 138. 



' For the form of the instructions here given we are indebted to 

 Professor Marshall Ward. 



* Or any of the solutions given on p. 172 of Zopf, Die Pilie. 

 Solution N is compiled from Elfving, Studien tiber die Einwirkung dei 

 Lichti auf die Pilze, 1890, p. 30. 



