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of rotation will go round together, then start into a quick 

 whirl, then vary or slacken, or pass into a furious whirl, 

 showing such fluctuation in their movements, that it would 

 require no great stretch of imagination to believe them pos- 

 sessed of animation — many will, when they touch that part of 

 the cell w T hich joins the arm, appear to receive some peculiar 

 impulse, as if they were electrified/ This description, which 

 is adopted from Mr. Varley, is not universally applicable, as 

 in many instances the chlorophyll never seems to move at 

 all. 



"Besides the circulation he had described, in which the 

 globules move independently of the other cell contents, he 

 must notice the phenomenon of rotation, in which the whole 

 materials are revolving on their own axis. This takes place 

 most frequently in the epidermis of the valisneria, and the 

 youngest shoots of the chara. In the former it commences, 

 usually, about two days after the leaf has been severed, and 

 continues during three days in all ; after which it ceases, and 

 never returns in the same place : it must be remarked, how- 

 ever, that it commences soonest in the cells nearest the incised 

 part of the leaf, and may sometimes have finished there 

 before it has begun in the more distant cells. 



" In the young shoots of chara this rotation is constantly 

 going on during vegetation; but it requires a high magnifying 

 power, and a subdued bght to see it well, as it is the mucus 

 alone which revolves, and a large nucleus or mass of albumen, 

 of such transparency that it can oidy be detected by the 

 shadow on its margins. 



"The phenomenon of rotation is as regular in different 

 cells, both as regards rapidity and constancy, as that of cir- 

 culation is the reverse. We may compare the former to the 

 drum of a machine, the latter to the irregular walk of prisoners 

 in an airing ground. 



" Some observers have divided the long cells of nitella (a 

 species of chara) into three or four parts by ligatures, and 



