104 THE CELL DOCTRINE. 



PROF, HUXLEY,* 1869. 



There is one kind of matter which is common to 

 all living beings, and that matter is " protoplasm" 

 the scientific name for " the physical basis of life." 

 In illustration from vegetable life, each stinging 

 needle or hair of the common nettle consists of a 

 very delicate outer case of wood, closely applied to 

 the inner surface of which is a layer of semifluid mat- 

 ter, full of innumerable granules of extreme minute- 

 ness. This semifluid lining is protoplasm, which thus 

 constitutes a kind of bag, full of a limpid fluid, and . 

 roughly corresponding in form with the interior of 

 the hair which it fills. When viewed with a suffi- 

 ciently high magnifying power, the protoplasmic 

 layer of the nettle hair is seen to be in a condition of 

 unceasing activity. Local contractions of the whole 

 thickness of its substance pass slowly and gradually 

 from point to point, and give rise to the appearance 

 of progressive waves, just as the bending of successive 

 stalks of wheat by a breeze produces the apparent 

 billows in a wheat-field. 



But in addition to these movements, and inde- 

 pendently of them, the granules are driven, in rela- 

 tively rapid'streams, through channels in the proto- 

 plasm which seem to have a considerable amount of 

 persistence. The currents in adjacent parts com- 

 monly take similar directions, coursing in a general 

 stream up one side of the hair and down the other, 



* Protoplasm j or, The Physical Basis of Life. A Lecture by 

 Prof. Huxley, delivered in Edinburgh, November 18th, 1868. 



