D4 SELECTED ESS A YS FROM LA Y SERMONS 



hair which it fills. When viewed with a sufl&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 corn by a breeze produces the apparent 

 billows of a corn-field. 



But, in addition to these movements, and independently 

 of them, the granules are driven, in relatively rapid streams, 

 through channels in the protoplasm which seem to have a 

 considerable amount of persistence. Most commonly, the 

 currents in adjacent parts of the protoplasm take similar 

 directions; and, thus, there is a general stream up one side 

 of the hair and down the other. But this does not prevent 

 the existence of partial currents which take different routes; 

 and sometimes trains of granules may be seen coursing 

 swiftly in opposite directions within a twenty-thousandth 

 of an inch of one another; while, occasionally, opposite 

 streams come into direct collision, and, after a longer or 

 shorter struggle, one predominates. The cause of these 

 currents seems to lie in contractions of the protoplasm w^hich 

 bounds the channels in which they flow, but which are so 

 minute that the best microscopes show only their effects, 

 and not themselves. 



The spectacle afforded by the wonderful energies prisoned 

 within the compass of the microscopic hair of a plant, which 

 we commonly regard as a merely passive organism, is not 

 easily forgotten by one who has watched its display, con- 

 tinued hour after hour, without pause or sign of weakening. 

 The possible complexity of many other organic forms, seem- 

 ingly as simple as the protoplasm of the nettle, dawns upon 

 one; and the comparison of such a protoplasm to a body with 



