204 DUTROCHET'S EXPERIMENTS. 



Penelope to the green nightingale, x^Y"?* taj8<ov ; and Simonides has 

 the expression x^<?>p a vx evf s amoves, green-necked nightingales ; Euripides, 

 again, mentions its yellow cheeks, avdav yewjwov. These various ex- 

 pressions, I am inclined to think, allude to the bird described in the 

 Field Naturalist's Magazine for February, 1833, under the name of 

 " The Arbour Bird," Sylvia polyglotta, Ranzani, (S. Hippolais of 

 Bechstein, but not of Temminck ; the S. Hippolais of the latter refer- 

 ing to the monotonous willow-wren, or ching-ching, of the Hon. and 

 Rev. W. Herbert and Mr. Sweet.) A preserved skin of the Polyglotta 

 is now before me : the bill is large, and formed like that of the nightin- 

 gale, which latter bird it also somewhat resembles in make ; in the hue 

 of its plumage, and in the colour of its eggs, it assimilates to the wil- 

 low-wren genus; and the structure of its nest connects it with the 

 fruit-eating warblers. Upon the whole, it is an intermediate and 

 highly interesting form, and its characters are too peculiar to allow of 

 its being placed in the same genus, with any other known European 

 warbler. I think the term Horticola, expressive of its habits, would 

 be a good generic designation, and the species may very appropriately 

 be termed Horticola polyglotta. 



Tooting, Surrey, April 19, 1833. 



EXPERIMENTS ON PLANTS TURNING TOWARDS LIGHT. 



BY M. DUTROCHET, MEMBER OF THE INSTITUTE, PARIS. 



IN order to ascertain the effect of light on growing plants, the stems 

 of onions and of leeks were taken up with their bulbs, and laid 

 horizontally on the ground, in a dark and dry place. These plants, 

 although taken out of the ground, continued to live for a long time ; 

 their stems became curved, and their upper end took a direction 

 towards the heavens. This happened in about ten days ; but being 

 repeated in the open air, three days were sufficient to produce the 

 direction. In the first experiment, light being wholly excluded, 

 gravitation only could have operated in giving the stem a perpen- 

 dicular direction, that power being the only one which is known to 

 act in a direction perpendicular to the horizon. Modifications of this 

 experiment were instituted, to be certain that humidity had no effect, 

 and the same result was obtained. In the prosecution of these 

 investigations, it also appeared that it was not merely the summit of 



