248 GENERAL BIOLOGY 



place in the protoplasm of the nerve. 1 Similar 

 electrical changes may be observed in other tissues 

 as well, but only when alive; a dead nerve or a 

 narcotized nerve gives no such reaction. This 

 electric response, which may be demonstrated also in 

 plants, has been referred to as the critical sign of life. 

 But Professor Bose of Calcutta has shown that metals 

 give a quite similar response, provided all strains have 

 been removed by annealing. A tin wire thus treated, 

 and " stimulated " by mechanical, thermal, or 

 chemical means, will show the same phenomena of 

 response that a nerve or a plant does. Bose's con- 

 clusions, which are very far-reaching, are that there 

 is no essential difference bet ween, organic and inor- 

 ganic matter, with respect to response. The differ- 

 ence between living and dead protoplasm, he thinks, 

 is probably the condition of the absence or presence 

 of permanent molecular strains, which is another 

 way of saying that dead protoplasm is relatively 

 stable, whereas the primary characteristic of living 

 matter is its lability. The primary distinction 

 between the response of living and of non-living 

 matter, as already pointed out, lies in the fact that, 

 in the former, the energy released by the response may 

 be many times greater than that of the stimulus. 



Individual Response to Unsymmetrical Stimuli. - 

 Heretofore we have considered environmental stim- 

 uli in a general way, as affecting all parts of the 



1 It has also recently been demonstrated that a stimulated nerve gives 

 off COj, indicating the nature of the chemical reactions taking place 

 within its substance. 



