422 



THE GUIDE TO NATURE. 



FOLDED LEAFLETS. OPENED LEAFLETS. 

 To show sensitive hairs. 



I found it interesting to run a finely 

 pointed instrument like a pin, or the 

 tips of my tweezers, along the line of 

 the central vein of each leaflet and 

 to see all the leaflets close. This sug- 

 gested that I should try to bring about 

 the movement without actually touch- 

 ing the central vein ; that is, touching 

 only the hairs, and I found that these 

 appendages may act as feelers. The 

 next thought was to photograph the 

 centre of one of these leaves so as to 

 show the arrangement of the hairs 

 along the central vein, lint I found 

 this is no easy thing to do. It was like 

 photographing a living animal, the 

 difficulty being in catching it and in 

 inducing it to remain quiet long 

 enough to accomplish the photograph- 

 ic exposure. I had to resort to subter- 

 fuge, or, in other words, to set a trap 

 for the plant about the same method 

 that one would use in catching a wary 

 animal. I took two glass slips, 

 two inches long and one and one- 



half inches wide and placing one 

 under a leaf, waited until it was 

 wide open, and then suddenly 

 clapped down on it the other glass 

 slip, thus catching it by a method simi- 

 lar to that old fashioned one of catch- 

 ing house flies between two shingles 

 smeared with molasses. As in catching 

 flies I found it difficult to be quick 

 enough to catch the leaf before it could 

 get away or, in other words, before it 

 started to close. After repeated trials 

 I succeeded and, binding the whole 

 together firmly, I obtained a photo- 

 graph which is really a silhouette, but 

 it shows well the hairs along the cen- 

 tral vein. 



Then I disturbed another leaflet, and 

 put it before the camera after the 

 leaves had closed. It was evident that 

 these hairs do act as feelers and inform 

 the plant that an enemy or a disturbing 

 element is near by. 



Slight disturbances are followed by 

 the closing of the leaflets only, but a 

 sudden jar causes the entire leaf-stalk 

 to bend downwards. I observed that 

 this bending was accomplished at one 

 particular part of the petiole, and I 



WHERE THE SUDDEN BENDING IS 

 DONE. 



