LIGHT REACTIONS OF A LITTORAL ARANEAD. 73 



Then a number of experiments were made to test the reactions 

 of the spiders to the rays of an ordinary student oil lamp placed 

 one foot or a foot and a half away from them, all these experi- 

 ments being made at night. Numbers were caught and placed 

 in small vials, which can be done without injury to them for 

 they are hard-bodied. Then a piece of smooth white paper was 

 laid horizontally upon the table, and kept free from sand or 

 other particles; on this paper four quadrants were marked, 

 the one nearest the lamp marked A, the one most distant from 

 it D and the other two quadrants C and B. A vial was then 

 uncorked and the spiders allowed to drop in succession gently 

 upon the center of the paper, each falling slowly on its own 

 drag line. With a pencil the course of each spider was then 

 marked upon the paper, which made a permanent record of all 

 movements of all individuals. On different nights a total of 

 107 spiders were thus tested, with the following results: 3 ran 

 into quadrant A, directly towards the light; 45 ran into quadrant 

 D, directly away from the light; 28 turned into quadrant B 

 and 31 into quadrant C, these accordingly at right angles to the 

 direction of the light. This proves negative phototropism to 

 the rays of an oil lamp, for only 2.8 per cent, of the individuals 

 ran towards the light. In these experiments it was purely a 

 matter of chance how the spider was oriented when it first 

 touched the paper. Of those that happened to touch it facing 

 the light almost all moved through an arc of a circle so as to get 

 into another direction and then continued their courses in almost 

 straight lines; there was a marked turning away from the source 

 of the light. 



Another experiment was made with diffuse daylight. Eleven 

 spiders were dropped in similar manner upon a piece of white 

 paper placed on a table in the northwest corner of a room, sun- 

 light entering the east window but not reaching the table. Ten 

 of the spiders turned directly away from the sunlight, and one 

 at right angles to it. This was then negative phototropism. 



In a third experiment spiders were dropped upon a piece of 

 white paper on which the sun shone directly, the sun being then 

 near the meridian (10.45 A.M.). In this case ten moved towards 

 the sunlight, one at right angles to it, and eight away from it. 



