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yock : observe that it is now above an inch distant from 

 it. You are surprised that 'you did riot perceive it 

 waik, for you looked at it more than once; the reason 

 of this is, because its progressive motion is as slow as 

 that of the hand of a clock. We may be curious to 

 know how the nettle performs it. All its body is ex- 

 ternally furnished with various orders of muscles : those 

 of the base go, like rays, from the centre to the circum- 

 ference ; others descend from the top towards the base. 

 These muscles are also canals, full ot liquor, which is- 

 sues out on pricking them : they are emptied and filled 

 at the pleasure of the nettle. By the exercise of these 

 muscles, or canals, the progressive motion is performed. 

 Let us follow the nettle when she is disposed to go for- 

 wards. Her base is circular. She swells the muscles 

 that are on that side whither she is tending. She injects 

 her l$TQor into them, which, by inflating, lengthens 

 them. They cannot extend themselves unless the edge 

 corresponding with the base shifts its place, and ad- 

 vances a little way : at the same time she loosens the 

 opposite muscles, and empties their canals. They con- 

 tiu'.-.i. 'I his they cannot do, except the edge of their 

 corresponding base goes in a little, and exactly in the 

 same degree as the opposite one projects. Such is the 

 mechanism whereby the first step of our nettle is per- 

 formed. In order to make a second, she causes the 

 base again to receive a circular form, by pulling up 

 equally all the canals : she afterwards repeats the same 

 operations we have just taken a view of. 



The whole progressive motion of nettles is not con- 

 fined to this. They have another method of walking, 

 which more nearly resembles that of insects : they are 

 able to make use of their horns like legs. But these 

 horns are on the upper part of their body : the nettle 

 is fixed by its base against the rock : How do these 

 horns perform the office of legs 1 The nettle you are 

 following will shew you the method. She turns herself 

 upside down ; the base abandons the rock, and the cone 

 is placed on its top : all the horns shoot forth, and you 



