14 BOTANY. 



(/) The passage from the condition in the last examples (the so- 

 called circulation of protoplasm) is an easy one to the cases where the 

 whole mass of protoplasm moves along the cell- wall as a broad stream, 

 passing up one side and down the other (the so-called rotation of pro- 

 toplasm). Common and well-known examples of this kind of mass-move- 

 ment occur in Chara, Naias, and Vallisneria. It may also (on the 

 authority of Meyen) be studied in the root-hairs of many land plants 

 e.g., of Impatiens Balsamina, Vicia faba, Ipomaa purpurea, Cucumis, 

 Cucurbita, Ranunculus sceleratus, and Marchantia polymorpha. 



NOTE. In the study of the structures treated of in Chapters I to V 

 inclusive, the student will do well to consult a recent laboratory man* 

 ual "Botanical Micro-Chemistry," by V. A. Poulsen (William Tre- 

 lease, 1884). 



