1 6 PROTOPLASM. 



to the matter of which the amoeba, the sarcode of the fora- 

 minifera, &c., is composed, and that which constitutes the 

 white blood-corpuscle and such bodies, but the matter 

 which is gradually assuming the form of tissue has been 

 considered to be of the same nature. The radiating fibres 

 of the caudate nerve-cells of the spinal cord have been 

 termed protoplasm fibres, and the outer part of the nerve- 

 cell with which they are continuous is composed of the 

 same substance. The axis cylinder of the dark-bordered 

 nerve-fibres and the fine ultimate nerve-fibres in peripheral 

 parts have been looked upon as a form of protoplasm ; but 

 it is hardly necessary to remark that, whatever may be the 

 nature of the material of which nerve-fibres and the outer 

 part of nerve-cells are composed4 it possesses properties 

 very different from those manifested by the amoeba, white 

 blood-corpuscle, etc., and is destitute of the powers which 

 characterize the matter constituting these bodies. Here 

 again we find the term protoplasm applied to different kinds 

 of matter or to matter in very different states. 



But unfortunately we have by no means exhausted the 

 confusion which has resulted with regard to protoplasm, for 

 the name has been applied also to the outer, hard, dead 

 part of epithelial cells and by implication to all correspond- 

 ing structures. 



Protoplasm of Huxley, 1869. 



Up to this time all observers have agreed in opinion 

 that the cell or elementary part of the fully-formed organism 



