240 



GENERAL PHYSIOLOGY 



exactly the same in plant-celis a;? in Fudzopi-xTa ; ITax Schtiltze 

 ('63) haj discussed very fully the analogy of protoplasmic move- 

 ment in the two cases. 



The amount of work that can be performed in amoeboid move- 

 ment has thus far not been ascertained, but the development of 

 energy does not appear ti > be considerable. 



iluscular movement is the specific form of movement of the 

 animal organism, by which apparently it is distinguished from all 

 plants. All the gi'oss and 

 rapid mass-movements of the 

 whole animal body or of single 

 systems of organs, all those 

 remarkable movements which 

 of all vital phenomena produce 

 most the impression of living, 

 depend upon the contraction 

 of muscle-fibres. Such move- 

 ments mislead ordinary ob- 

 servers into ascribing to 

 animals a higher stage of life 

 than to the plants, the latter 

 being considered to stand 

 much nearer to lifeless nature 

 than to the animals. 



In contrast to amoeboid 

 protoplasmic movement, mus- 

 cular movement is especially 

 characterised by the fact that 

 its factors are co-ordinated in 

 space, in so far as the particles 

 of a muscle-fibre shift them- 

 selves in one definite direc- 

 tion. Of cottrse it can be 

 said that in a long, straight, 

 filose psettdopodium the par- 

 ticlesflowlikewise in a definite 

 direction ; but this direction 

 is not continual, for, in re- 

 traction the particles mingle 

 again with others and separate 



from one another in all possible directions. In contrast to this, 

 the particles that in a muscle-fibre are the seat of contraction- 

 phenomena are constantly present as special structures in 

 the rest of the cell-protoplasm and cannot directly mix with 

 it. It is customary to tenn the whole muscle-cell a musch- 

 I'hi't, and these specially difterentiated contractile strips in it 



Fio. 99. 



CeU from a stamen-hair of Traihifantia 

 '•< <\'iitica. A, Quiet protoplasmic str«;uniiig in 

 the strands of protopl;\sni ; £, the prvcoplasm 

 has coutr:\cted into lumps and globules at a. ^. 

 <■. rf. (After KUhne.) 



