The Cilium. 179 



According to Davis (1904, p. 712), the kinojjlasm is homogeneous 

 in structure, either minutely granular or consisting of delicate 

 fibrillae composed of very small granules placed end to end. Its 

 homogeneous character is shown in the cell membranes, while the 

 fibrous condition appears during cell activity and then disappears. 

 On page 449 Davis says : "Kinoplasm runs through cycles in which 

 the structure passes from a granular condition to a fibrillar and back 

 again into a granular state." He admits that the fibrillae may noh 

 disappear, but simply be arranged in a closely packed network which 

 is invisible under the microscope. All protoplasmic movements are 

 due to the contraction of the kinoplasmic fibrillae. Although there 

 is much about the kinoplasmic structure that is not understood, there 

 is much in this theory of the structure of protoplasm that is attrac- 

 tive. 



Hyaloplasm Active, Spongioplasm Inert. 



One of the most peculiar theories developed to explain protoplasmic 

 movements appeared in the year 1883. In this theory Brass (1883 

 and '84) and, soon after, Leydig (1885) exactly reverse the concep- 

 tion of the adherents of the reticular theory. Instead of the reticu- 

 lum, the spongioplasm, according to these two writers, it is the fluid 

 part, the hyaloplasm, that is contractile. In its activities is to be 

 found an explanation of all protoplasmic movements. Few investi- 

 gators have been inclined toward Leydig's hypothesis. Rhode (1890 

 and '91), Griesbach (1801) and Schiifer (1887, '91, '93 and 1904) 

 about complete the list. Schafer's views have been criticized by 

 Blitschli (1892) and recently by Putter (1903), especially in its 

 application to the cilium. Although Schiifer (1904) answers Put- 

 ter's criticism, we find little in his discussion that warrants us in 

 accepting his view. Recent investigations seem to prove conclusively 

 that his position is untenable. 



Schafer's view may be summed up briefly as follows : Protoplasm 

 is composed of two distinct substances, spongioplasm and hyaloj^lasm. 

 "Spongioplasm has a reticular or sj)onge-like arrangement, an affinity 

 for staining fluids, is firmer than hyaloplasm, but perhaps not actually 

 solid, and is in all probability highly extensible and elastic. Hyalo- 

 plasm, on the other hand, is structureless, has little or no affinity for 

 stains and is highly labile and fluent. It is by the active flowing of 



