Habit and its relations to the nervous system in the earthworm

Abstract

This is a preliminary report of an investigation now in progress, the purpose of which is (a) to demonstrate whatever ability the earthworm may have to acquire habits of a certain order; (b) to discover the characteristics of any habits which appear; (c) to enumerate and evaluate the various external and internal influences on habit-formation; (d) to ascertain the degree of permanency of the habits and (e) to discover their relations to the anterior ganglia (brain).

By means of a T-shaped maze constructed from plate glass, specimens of the manure worm, Allolobophora fetida, were tested. The maze was placed with the stem directed toward the light. Across one of the arms a piece of sandpaper was placed and, just beyond it, a pair of electrodes. The other arm was left open so that the worm might escape to an artificial burrow. The worms were driven into the T by light and the chief motive for escape therefrom was the tendency to avoid light. It was the purpose of the test to demonstrate (a) any ability which the manure worm may possess to acquire a direction habit and (b) to associate the tactual experience of contact with sandpaper with the electrical shock which regularly followed the tactual stimulus in case the worm continued to move forward after reaching the sandpaper.

Trials were made in daily series varying in number from five to twenty. The five-trial series were found, on the whole, most satisfactory.

Referring now exclusively to the results obtained for a single worm which has been under observation since October, 1911, the following data may be presented. (I) Allolobo@hora is capable of acquiring certain definite modes of reaction. (2) Modifications appear as the result of from twenty to one hundred experiences.