260 LETTER-FILES OF S. W. JOHNSON 



your Papa, your Mamma and all the Dictionary that has Pr 

 words in it, and get a working knowledge of the words under- 

 scored above. That done, we go on to remark that protoplasm 

 is always, everywhere under favorable circumstances sensitive, 

 and capable of motion when touched, i.e. when moved, and 

 can move of itself. The sensitive plant moves when you move 

 it, the boy keeps moving when the motion is made and sec- 

 onded to stop his "moving, any more in that way, just now!" 

 The sensitive plant moves because its protoplasm moves, and 

 that 's what 's the matter with the boy ! 



Now you will ask why don 't other plants move ? The cor- 

 rect answer is ' ' they do move ' ' ! But most common plants 

 move much less quickly and far less extensively than the sen- 

 sitive plant does. Such animals as live in a hardshell house 

 that they carry around with them, like the turtle, armadillo 

 and alligator, move much less noticeably than the small boy 

 whose awful dad has to build, and often [repair], the cloth- 

 houses and the brick houses that said s. b. dwells in when he 

 does not go a-swimming. So the clothes in which the modest 

 mimosa-protoplasm is dressed are much less snug-fitting — 

 have not so much whalebone, buckram, leather and pilot cloth 

 as coarser, vulgar plants like for their garments. 



There are many plants that are sensitive enough to make 

 some slow motion when touched roughly. One such plant is 

 a common "weed" about New Haven, with handsome yellow 

 flowers and leaves very like those of the "sensitive plant" 

 you have asked about. Many — perhaps most, plants when 

 seen under a microscope are found to have visible motions 

 going on, in their insides, somewhere, especially in the young 

 parts where they are not too "hide bound." The sensitive 

 plant, like the irrepressible boy, becomes less sensitive as it 

 grows old. The boy, you know, when he gets to 90 or 100 years 

 old isn't more sensitive than a burdock or a pumpkin. 



In the sensitive plant the leaves are arranged like this 

 sketch, where a shows the untouched and h the touched leaves. 

 From c I have drawn a line to the point where the four leaves 



