32 E. H. HARPER. 



though they may carry the worm to a considerable distance and 

 enable it to distract the enemy. They are a conspicuous example 

 of the character of most movements of the earthworm, which 

 belong to its limited life outside the burrow. 



CONCLUSIONS. 



The method of reaction to light of the earthworm is far 

 removed from the sort of "trial and error method" of the Infu- 

 soria, as analyzed by Jennings. Its avoiding reaction in strong 

 light is of the nature of a definite reflex which causes it to turn 

 directly away from the stimulus, if the whole body is in the light, 

 or to retreat into its burrow, if only the anterior end is stimu- 

 lated, or go forward if the posterior end alone is stimulated. 

 Methods of trial and error in reaction to light and other ordinary 

 stimuli have clearly been supplanted by more definite responses 

 in all but the Protozoa and certain other low types of animal 

 life. The earthworm's reactions to stimuli, mechanical, thermal, 

 chemical, are in general such as its nervous system and muscu- 

 lature would lead us to expect. The occurrence of random 

 movements in response to all but very strong light is the out- 

 come of the undeveloped condition of its organs of light per- 

 ception, not to the want of a nervous system and musculature 

 adapted for such simple reflexes. Diffuse organs of light per- 

 ception may not respond definitely to a localized stimulus unless it 

 is a very strong one. The trial and error method of its responses 

 to relatively weak light are exceptional in character in com- 

 parison with its reactions to other ordinary stimuli. Its archaic 

 type of end organs for light gives rise to a type of behavior which 

 is to be regarded as primitive. For the trial and error method 

 is clearly supplanted in the ascending scale of animal life, by 

 reactions of a definite nature, in the case of the simple responses 

 to the ordinary stimuli. 



SUMMARY OF RESULTS. 



1. PcricliiCta bcrmudensis (Beddard) is an exotic earthworm 

 found sometimes in greenhouses. Its active habits are one of its 

 chief characteristics. 



2. The body is less sensitive to light when contracted than 



