96 THE CELL DOCTRINE. 



tissues, according to the French school. Such pe- 

 rusal cannot fail to convince the reader also of the 

 accuracy of description of the fully formed elements 

 described by Robin. 



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 semi-fluid 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 grain \by a breeze produces 

 the apparent billows of a grain-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- 



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

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



