172 0. P. Bellinger. 



Introduction : Statement of Problem. 



A complete title for this paper would be : The Cilium studied com- 

 paratively as a test of microscopical methods and a key to the struc- 

 ture of contractile protoplasm. 



The attempts of recent investigators to resolve the activities of 

 contractile structures into phenomena due to alterations in the sur- 

 face tension of a complex fluid are proving as unsatisfactory as the 

 older attempts to identify contractility with chemical and electrical 

 processes. Those who approached the problem from this standpoint — 

 Berthold, Quinckne, Biitschli, Rhumbler, Jensen and others — used 

 the Amoeba with its activities as ''Ausgangspunkt" for their re- 

 searches. Unfortunately they did not determine the real character 

 of the movements here, and, therefore, their theories of protoplasmic 

 movement based on the supposed activities of the protoplasm of the 

 Amoeba have little value. The work of Jennings (1904) and Del- 

 linger (1906) has shown their position to be untenable. 



Instead of seeking in the movements of the Amoeba for a key to 

 the structure of contractile protoplasm, the present study turns to 

 the cilium. Here we find contractile tissue, microscopically speaking, 

 in its simplest form. As the cilia are outgrowths of the cell proto- 

 plasm, there is every reason to suppose that exactly similar structures 

 may exist within the cell body. Until we have applied to the proto- 

 plasm of the cell the methods best adapted to preserve and demon- 

 strate the character of cilia, we are not justified in appealing to indefi- 

 nite and undemonstrable fluids to do the work of solids. 



The investigation falls naturally into two parts. The first is con- 

 cerned with the best methods of preserving and demonstrating the 

 structure of cilia. The second is the apj)lication of these methods to 

 contractile protoplasm as represented in the Protozoa, smooth muscle 

 and striped muscle. 



I wish to acknowledge my indebtedness to Dr. C. F. Hodge, under 

 whose direction the work has been done, for many helpful sugges- 

 tions and criticisms ; to Mr. L. N. Wilson, Librarian of the Univer- 

 sity, for aid in securing the literature, and to Dr. F. N. Duncan foj- 

 permission to use part of his unpublished manuscript. 



