The Cilium. 175 



framework, which was the beginning of our reticular theory of the 

 structure of protoplasm, most of the investigators of his time were 

 simply content to refer in a general way to contractility as an ultimate 

 factor, not attempting further analysis. 



Contractile Protoplasm Reticular or FiJirHlar. 



Although the early writers were united in ascribing to protoplasm 

 the property of contractility, it was first with Briicke that this con- 

 tractile substance took on organization. It is not very clear just 

 what his views were, but it is evident he thought that protoplasm was 

 made up of a firm, contractile i*eticulum bathed in a fluid. Two 

 years later Cienkowsky assumed a similar structure for the plasmodia 

 of the myxomycetes. 



It was perfectly natural, therefore, for Heitzmann when he found 

 a reticular framework in the protoplasm of Amoebae and the white 

 corpuscles of a number of animals (Flusskeckers, Tritons and Men- 

 schen) to ascribe to this reticulum contractility, anl to see in it an 

 explanation of all protoplasmic movements. (Heitzmann, 1S73.) 

 He also agreed with Briicke and Cienkowsky in that he thought this 

 reticulum bathed by a non-contractile fluid. Biitschli (1892, p. 105) 

 questions Heitzmann's observations, and thinks we should attach 

 little value to them. However this may be, it is quite possible he 

 came much nearer divining the true structural character of proto- 

 plasm than did Biitschli himself. A large number of investigators 

 since Heitzmann's time have, in the main, agTced with him that pro- 

 toplasm has a reticular or fibrillar structure and that it is the frame- 

 work or fibrillae that is contractile, referring all phenomena of 

 movement (locomotion, change of form, ciliary movement, etc.) to 

 these structures.^ Among those holding this point of view are to be 



"We can trace back to an early date observations on the reticular or 

 fibrillar structure of certain cells. Thus for the muscle, according to Hein- 

 denhain, we find Lauth (1834), Schwann (1839), Henle (1841) and Hoist 

 (1840). spealving of "feiuere und parallele Fibi'illen." Later the extensive 

 works of Wagner (18(13) and Rouget (1863) in the Gastropods, Nematodes, 

 Lumbricus, and various higher animals, brought out beautiful fibrillae in 

 the smooth muscles of these forms. Heidenhain has recently gone over the 

 literature covering the muscle and I refer the reader to him for further 

 history of this subject. 



