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The' famous series of experiments in mutation started by Pro- 

 fessor de Vries about twenty years ago, were shown me in a very 

 interesting way by the young man who has charge of them. The 

 plants are compactly housed in two adjoining enclosures, which 

 together form a square, the whole being covered with wire 

 netting. Here I saw Oenothera gigas, 0. rubrinervis, O. lata, 

 nana, etc., all in perfect order and perfectly protected. The rust 



but the young rosettes of 0. nana were found to be attacked by 

 an unknown fungus that causes the top leaves to wilt and die. 



A small plantation of five-leaved clover, with some of the leaves 

 pinnate, was of special interest to me, because I first learned of 

 Professor de Vries' experiments with clovers while studying 

 agriculture at college, as long ago as 1885. These experiments 

 with economic plants, also, appear to have a decidedly practical 



