STRUCTURE AND PROPERTIES OF PROTOPLASM 61 



accessible for Nilella in this book at page 21, and for Chara, Vallisneria, 

 and Elodea in Davenport's " Experimental Morphology," 226. 



The student should now, calling the literature to aid, ascer- 

 tain what is known as to classification of the forms of movement, 

 how widely it prevails through living cells, what is known or 

 (more properly) what is supposed as to its meaning to the plant, 

 and what its physical basis (energetics) is. The latter matters 

 he can best follow through the works of Ewart and Butschli, 

 and he should know something of the artificial foams, developed 

 by the latter, which simulate the protoplasmic movements. 



During the foregoing study the student should take note 

 of any appearances which testify to the ultimate mechanical 

 structure of the Protoplasm, — whether this is a finely fibrous 

 mass soaked with liquids, as the older views supposed, or an 

 emulsion of liquids holding solid bodies in suspension, as the 

 newer conception, especially advocated by Butschli, main- 

 tains. It is possible this problem will be solved by the ultra- 

 violet microscope, a very new instrument using such short light 

 waves as to give clear definition to extremely minute objects; 

 and the student should follow henceforth the developments 

 in this line of investigation. 



There is another method yielding knowledge of protoplasmic 

 structure, viz., the killing and staining of the substance by the 

 methods used in histology, especially in cytology. The student 

 should make himself acquainted, preferably through study of 

 cytological preparations, with the structures thus shown to exist 

 in the dead Protoplasm, and with the probabilities as to their 

 existence in Protoplasm while alive. The details of cytolog- 

 ical phenomena are, from the present point of view, obviously 

 not important. 



The study of any, even of all, of the above-mentioned mate- 

 rials gives a knowledge of living Protoplasm, which, while accu- 

 rate, is yet very limited, and it should receive extension by further 

 study. This should be observational, if that be practically 

 possible, and literary if it be not, and should embrace a wider 

 range of materials, representing the substance under more special, 



