LIVING PIvANTS 



low beings. The struggle for existence is by 

 no means a fiction, even with an amoeba. 

 What is the provision, the device, the method 

 by which the organism is enabled to success- 

 fully meet the destructive and levelling ten- 

 dencies of the world outside itself? It is to be 

 found, without question, in that general prop- 

 erty' of all living matter tisualh' designated 

 as irritability. If a liit of the leaf of water- 

 weed, the hair from a pumpkin stem, an 

 amoeba, or any similar vegetable or animal 

 structures be placed under the microscope 

 and irritated in some manner, say b^^ a light 

 tap or shock, sudden change of temperature, 

 an interrupted current of electricity, etc., the 

 soft protoplasmic portion Avill shrink and 

 change form in a characteristic way that 

 thoroughl^^ justifies us in saying that it makes 

 a sensitive response to the stimulus. After a 

 time the normal form and activity are regain- 

 ed, and another irritation will be followed by 

 another visible response. If, however, the ir- 

 ritation be too severe — if the tap be too 

 strong, the change of temperature too great, 

 or the electric shock too intense — the convul- 

 sion which follows will be mortal, andnofav- 

 orable environmental conditions or supply of 

 energy will again restore the life that has dis- 

 api)eared. The protoplasm or animalcule is 

 as genuinely dead as the man who has been 



