94 



THE AMERICAN NATURALIST [Vol. XLII 



It has been conceded generally that fasciations are 

 due to changed conditions of nutrition. Nestler, de Vries, 

 Goebel, Sorauer and many others agree that they are 

 induced either through an increase of nutrition of the 

 entire plant or of that of certain shoots through the re- 

 moval of others. In other words, it is due to a change of 

 the chemical and physical conditions within the cell. The 

 influence of chemical substances upon plant and animal 

 cells has been widely studied. Among the best known are 

 the experiments of Johannsen 53 in which lilac bushes and 

 other flowering shrubs, of which we see the branches in 

 the florist's windows in early spring, under proper con- 

 ditions of moisture and temperature, were for a certain 

 length of time exposed to the action of ether or chloro* 

 form, after which they bloomed several months earlier 

 than normally would have been the case. Loeb's experi- 

 ments on the cleavage of unfertilized eggs of the sea 

 urchin, after having been treated with magnesium chlo- 

 ride, are too well known to make it necessary to go into 

 detail. The same thing is true for his studies on the 

 influence of the lack of oxygen and resultant modifica- 

 tion in the cleavage of eggs of Echinodermata. Migula's 

 experiments on the influence of dilute acid solutions on 

 algal cells, Richards' work on the development of fungi 

 under the influence of chemical stimuli, and especially 

 the work of Sabline on the influence of external agents 

 on the roots of Vicia Faba show that external influences 

 may bring about profound nuclear changes. Still better, 

 this is brought out by the injection experiments of Mac- 

 Dougal, 54 who was able to produce new species through 

 the injection of dilute salt solutions into the capsules of 

 evening primroses. And in the case of hyphae of many of 

 the Chytridiaceae, which bring about abnormal cell di- 

 visions in the tissues of the host plant, the protoplasm of 



53 Johannsen, W. Das Aetherverfahren beim Friihtreiben, 2« Aufl., Jena 

 1907. 



" MaeDougal, D. T., A. C. Vail and G. H. Shull. Mutations, Variations 

 and Relationships of Oenotheras. Carnegie Institution of Washington 



