The Cilium. 177 



with cell division are coutractile fibrillae. These flbrillae arise from the 

 reticulum of the protoplasm, during division, by the breaking down of 

 the cross connections. After division they return to the reticular condition 

 by anastomosing. 



Van Beneden (1876 and 1883) held that the protoplasm contained a cou- 

 tractile reticulum and that it was a modification of this that formed the 

 asters in ova. 



Apathy (1891) holds to the fibrillar structure for nerves and muscles. 

 He supports his views by later investigations. 



Ballowitz, through numerous investigations between 1880 and 1890, gave 

 very strong support to the fibrillar theory. Working with the spermatozoa 

 he found evidence that convinced him of the fibrillar nature of contractile 

 protoplasm. He believes that wherever we have contractility, flbrillae are to 

 be found. 



To go on through the list of contributions favoring this theory would 

 take too much space. I will mention, however, some of the more recent 

 papers bearing on this conception. 



Schenck (1897 and 1900) came forward as an opponent to the fluid 

 theory of protoplasm and as an advocate of fibrillar protoplasm. He thinks 

 that Verworn's contractile fluids are not sufficient to explain protoplasmic 

 movements and that contractile protoplasm (in the amoeba as well as 

 elsewhere) "muss eine bestimmte Structur habcn, darf nicht als Flussigkeit 

 angesehcn iccrden." And at another place "die contractile Suhstanz 

 fest ist." 



The drawings of Arnold (1898) show beautiful fibrills in a large number 

 of cells. He holds that this is the true structural character of proto- 

 plasm. 



Allen (1903) working with the dividing pollen mother-cells of Larix holds 

 that the fibers of the spindle arise from fibrills already present in the cell. 

 That these fibers are contractile and that they control the activities of the 

 cell. He argues against the view that they are precipitations as the result 

 of killing. 



Parker (1905) sees no reason why cilia might not be fibrillar and believes 

 that their activities are best explained on the basis of such a structure. 



Kunstler (1906) shows a beautiful reticular network in bacteria. 



Hartmann (1906) thinks the active contractile part of protoplasm is 

 fibrillar. 



Duncan, working in this laboratory, has come to the conclusion (held by a 

 number of writers) that the contractile elements in smooth muscle are 

 fibrillar. Although he has not published his work the examination of a large 

 number of forms has already been made and in every case he is able to 

 demonstrate such structures. 



In two investigations from this laboratory on the Amoeba, one published 

 jointly with Dr. C. F. Hodge, the author is of the opinion that the move- 

 ments of this form are only to be explained by the presence of a contractile 

 framework and the last paper (Functions and Structures in A. proteus) col- 

 lects the evidence for such structure. 



