11 



guished, and yet the fonner havo the power of locomotion 

 and other niovenient.s. 



The human tlesh is competent to heal slight injuries bv its 

 vital action ; the same is equally true of vegetable tissue 

 which has no nerves and yet can heal greater injuries. Irri- 

 tation of the skin has been known to produce various kinds 

 of tumors in man and beast, especially in horses and dogs; 

 various outgrowths on Howers, roots and stems result from 

 the same cause. 



The hair of a horse where the skin is galled by the har- 

 ness freiiuently changes from l)rown or black to white ; the 

 color of a leaf may be altered by an injury of the stem or 

 petiole. 



To show more fully the analogy existing between nerve 

 in animal and irritability in [)lant, we submit the following 

 quotations : 



"The property of conductivity (of transmitting a condi- 

 tion of activity aroused in one part by a stimulus to any 

 other portion) is exhibited l)v a vast variety of forms of 

 cell-protoplasm, and bi/ plants as well as animals. 



"In the case of plant-cells and in certain forms of muscle- 

 cells about which there is a more or less detinite wall or 

 sheath, there are little bridges of protoplasm binding the 

 cells together." (Am. Text-Book Physiology). 



There is an irritability of muscular tiber distinct from irri- 

 tal)ility of nerve. This independence of irritability is 

 proved in many ways : 



"By the use of the drug curare we are enabled to prevent 

 the nerve impulse from reaching the nuiscle, and when we 

 have done this we tind that the muscle is still able to re- 

 spond to direct excitation, with all forms of irritants, viz., 

 electrical, mechanical^ thermal, and chemical." (Am. Text 

 Book Physiology ) . 



"Some parts of muscles, such as the lower end of the 

 sartorius, and many muscular structures which have no 



