370 PEOF. TH. W. ENGEIiMANN. 



Physiology of Protoplasmic Movement.^ 



By 



Prof. Dr. Tli. W. Engelmann, 



in Utrecht. 



I. Introduction. 



Living protoplasm possesses in very many instances the 

 inherent property of moving with a rapidity which is perceptible 

 with the aid of the microscope. 



The movements, which show themselves by a change of 

 form and internal arrangement of the protoplasmic masses 

 while the volume remains apparently unchanged, may be 

 also artificially produced or influenced by what are called 

 stimuli. 



The existence of these movements is an intrinsic part of the 

 general conditions of life. 



In this they agree with muscular and ciliary movements, 

 with which, indeed, they are closely connected by nume- 

 rous transitional forms. They must be classed with both 

 the latter varieties of organic movement as phenomena of 

 contractility. 



The special character of protoplasmic movements lies in 

 this, that the particles of the contractile mass move, as a rule, 

 not in relation to any fixed position of equilibrium, but can 

 change their arrangement and position (and this apparently 

 voluntarily) as do the moving particles of a fluid substance. 

 Further, the impulse to such movements does not normally 

 come from without, but originates in the moving particles 



* Translated from Hermann's ' Handworterb. der Physiologic,' by A. G. 

 Bourne, B.Sc. 



