ANIMALS AND PLANTS. 165 



The results of recent inquiries into the structure of 

 the nervous system of animals converge towards the con- 

 clusion that the nerve fibres, which we have hitherto 

 regarded as ultimate elements of nervous tissue, are not 

 such, but are simply the visible aggregations of vastly 

 more attenuated filaments, the diameter of which dwin- 

 dles down to the limits of our present microscopic vision, 

 greatly as these have been extended by modern improve- 

 ments of the microscope ; and that a nerve is, in its es- 

 sence, nothing but a linear tract of specially modified 

 protoplasm between two points of an organism one of 

 which is able to affect the other by means of the com- 

 munication so established. Hence, it is conceivable that 

 even the simplest living being may possess a nervous sys- 

 tem. And the question whether plants are provided with 

 a nervous system or not, thus acquires a new aspect, and 

 presents the histologist and physiologist with a problem 

 of extreme difficulty, which must be attacked from a 

 new point of view and by the aid of methods which 

 have yet to be invented. 



Thus it must be admitted that plants may be con- 

 tractile and locomotive; that, while locomotive, their 

 movements may have as much appearance of spontane- 

 ity as those of the lowest animals; and that many ex- 

 hibit actions, comparable to those which are brought 

 about by the agency of a nervous system in animals. 

 And it must be allowed to be possible that further re- 

 search may reveal the existence of something compara- 

 ble to a nervous system in plants. So that I know not 



