VEGETABLE CYTOLOGY 



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of Mimosa, Oxalis, Drosera, Desmodium and Dioncea muscipula ex- 

 hibit this phenomenon to a marked degree. A few instances only 

 will be considered. When the tendrils of climbing plants come into 

 contact with the uneven surface of solid bodies they are induced to 

 coil. When the tentacles on a modified leaf of the Sundew (Dro- 

 sera) are stimulated mechanically by an insect or artifically they are 

 induced to curve over. If a good plant of the Venus Fly-trap (Dioncea) 



PiG-32. Mimosa Spegazzini. After the application of a stimulus. Compare 

 with Fig. 31. (After Steckbeck.} 



is selected, it will be seen to possess leaves, the terminal portions 

 of which are modified as traps for catching insects (Fig. 30). Hairs 

 will be seen projecting from the upper surface of each valve of the 

 hinged blade. If one of these hairs is touched with a pencil no re- 

 action will be evident but if after a lapse of twenty seconds the hair 

 is touched again, the 2 valves close. If the stamens of Berberis be 

 touched near the base during their pollen shedding stage they will 

 be observed to curve toward the stigma. 



