THE STRUCTURE AND PROPERTIES OF PROTOPLASM. 53 



IMIH >KTANT LITERATI' RK. 



The standard general works (especially Pfeffer's Physiology). 

 Wilson, E. B. Structure of Protoplasm. Science, 10, 33, 1899. 

 Venvorn, M. (translated by Lee). General Physiology, 55- 



i 3 6. 



Goodale, G. L. Protoplasm and its History. Botanical Ga- 

 zette, 14, 235, 1889. 



Biitschli, O. Protoplasm and Microscopic Foams. (Reviews 

 in Nature, 48, 595, 1893, and in Science, 2, 893, 1895.) 



Section 2. The Relations of Protoplasm to External Condi- 

 tions. 



In order to test the effects of external conditions and influ- 

 ences upon living Protoplasm, it is needful to use some method 

 by which the responses to those conditions and influences may 

 be made visible. The movement of circulation or rotation of 

 the cytoplasm in the cells of certain plants is extremely sensi- 

 tive to some external influences, and hence offers a convenient 

 test. It is of course necessary first to become familiar with this 

 movement as it occurs under normal conditions. 



6. What is the general character, the extent, the constancy, 

 the approximate rate, the places of greatest activity of the move- 

 ment in the protoplasm of (a) the stamen-hair of Tradescantia 

 virginica, and (b) the tip-cells of Nitella? 



Answer by annotated diagrams and concise descriptions. 



Mount on a slide in which a sligJit hollow is ground, 

 or support the cover on tiny legs of wax, so tJiat it may 

 not press upon the object. 



In what are the two alike as to the movement, and in what 

 different ? 



What is your opinion as to the use or meaning of the move- 

 ment? 



Is this rapid movement of wide occurrence? 



