The Plant Cell 33 



Cell-forms. 1 - Study parenchyma in the young stem of 

 Indian corn, or in the pith of an herbaceous plant, also collen- 

 chyma in the peripheral portion of a stem of wild carrot or 

 squash. Sclerotic cells may be easily identified in the gritty 

 portion of the fruit of pear. Tracheids and tracheae may be 

 studied by means of longitudinal sections of almost any woody 

 plant, grape vine and squash showing, particularly, ducts of 

 considerable size. These plants are also good for an examina- 

 tion of sieve tubes. 



Cells such as the tracheids may be conveniently studied 

 after maceration. Place sections of the desired material in very 

 strong or concentrated chromic acid for about one minute, or 

 until thoroughly limp and easily teased apart ; then wash and 

 tease out, or mount immediately, and separate the cells one 

 from another by gentle pressure upon the cover-glass. 



Protoplasmic movement. - - Following the general indications 

 in the text, study types of protoplasmic movement in the cells 

 of such plants as Nitella and Elodea ; hairs of Tradescantia, 

 of a cucurbit, or of Gloxinia; and the young hyphse of any 

 common black mold, Mucor. 



Use the most favorable material for further observation upon 

 the effects of temperature upon movement, employing a tem- 

 perature stage in determining the rate of movement at tem- 

 peratures varying from towards the minimum to an approximate 

 maximum. Plot a curve of the results. 



REFERENCES 



BUTSCHLI, O. (Eng. Ed., transl. by E. A. Minchin.) Investi- 

 gations on Microscopic Foams and on Protoplasm. 379 

 pp., 23 figs., 12 pis., 1894. 



1 It is considered important that students not qualified in anatomy or 

 histology should devote several laboratory periods to a study of the cell 

 and cell-forms. Reports based upon their own observations may be 

 supplemented by a more complete review of the subject as presented in 

 Stevens, Strasburger, Vines ("Text-book of Botany"), or other suitable 

 text. 



D 



