PROTOPLASM. 369 



But a large part of the tissues which make up the bodies of adult 

 animals have, in a great measure, lost their resemblance to the proto- 

 plasm from which they were derived, through an extreme development 

 which has resulted in tissues quite unlike each other some of them, 

 as the bones, for example, evidently serving a purely mechanical pur- 

 pose in the body ; and it may be said that a comparatively small pro- 

 portion of the tissues of the body are, strictly speaking, living. Pro- 

 fessor Beale classifies all the material of the tissues, and even of the 

 ultimate cells from which the tissues are derived, under two heads, as 

 formative and formed that is, matter which has the power of pro- 

 ducing new matter like itself out of pabulum or food, and that which 

 has no such power, but which has been produced by the former. He 

 considers that a muscle-fiber is not, like the protoplasm which produced 

 it, living ; and that the nerve-fiber also consists of formed material of 

 which protoplasm is the builder. 



In accordance with this view, only the lowest that is, the nutri- 

 tive processes can be regarded as truly vital. The higher functions 

 performed by the perfected tissues the bones, the muscles, and the 

 entire system of nerve-fibers and nerve-centers, including the brain 

 are mechanical rather than vital ; the character of the function in each 

 case depending on the character of the mechanism, i. e., on the par- 

 ticular relations of the parts concerned. 



Muscle-tissue, for example, has but a single and simple physio- 

 logical property, the power of change of form called contraction, and 

 even this is a function of formed material rather than of living mat- 

 ter ; but, through the mechanical relations of bones and tendons, of 

 joints and ligaments, of associated and opposing individual muscular 

 bundles, all the complicated and varied movements of the body are 

 brought about. 



The action of muscle is one and the same, whether it be expended 

 in the grosser movements of locomotion, in the finer manipulations of 

 the skilled artisan and the musician, or in the still more delicate ad- 

 justments of the vocal cords, by means of which the exquisite modu- 

 lations, almost infinite in variety, of the voice of a Patti or a Campa- 

 nini are produced. 



These various adjustments are evidently mechanical in their nat- 

 ure. The so-called vital processes processes identical with those 

 taking place in the simplest animal that lives, and in the very grass 

 beneath our feet, perform a comparatively humble part in the produc- 

 tion of the vast results. The vital processes are concerned in the 

 building up of the tissues and organs produced by and from proto- 

 plasm out of the food supplied to it ; and the chemical changes in- 

 volved in the breaking down of the tissues furnish the initial force in 

 each case ; but the actual forces manifested are due to transformations 

 of this initial force brought about by the complicated mechanism which 

 this force serves to set in operation. 

 vol. xxi. 24 



