176 FREAKS OF PLANT LIFE. 



of the fact of heliotropism, plants had to be selected 

 which were known to be peculiarly sensitive, and also 

 readily available and of convenient size. The young 

 seedlings of the canary grass (Phalaris canariensis) 

 were selected as fulfilling the conditions, just after 

 they appeared above the soil. Of course there was 

 nothing particularly sensational in such experiments ; 

 they did not make a great show, and produced no 

 very startling results, nothing greatly beyond the 

 confirmation of what was previously known. Yet 

 they are not without their interest, and especially 

 those which were made with the view of testing the 

 small amount of light necessary to induce helio- 

 tropism. A pot of these seedlings, which had been 

 raised in the dark, was placed in a dark room at the 

 distance of four yards from a small lamp. Within 

 three hours the shoots were perhaps slightly curved 

 to the light, but so little as to be doubtful. In rather 

 more than seven hours all were plainly bent towards 

 the light. Now, the light was so feeble at the 

 distance named that the Roman figures could not be 

 distinguished on the white face of a watch, and no 

 shadow was cast by a pencil held upright on a white 

 card, so that the amount of light diffused must have 

 been exceedingly small, and yet it did not fail to 

 exert its power after upwards of seven hours' 

 exposure. Similar experiments were performed at 

 greater and at less distances, and in a variety of 



