RECORDS OF MEETINGS 269 



F. Lyman Wells, A Xote ox the Eetentiox of Practice. 



Darwin Oliver Lyon, A Comparative Study of the Illusions and 



Hallucinations of Dementia Pr^ecox and 

 Manic Depressive Insanity. 



Summary of Papers 



Dr. Krueger's paper has been published on page 158 of Volume X of 

 the Journal of Philosophy. 



Dr. Dodge's paper has been published in the Psychological Review 

 for January, 1913. 



Dr. Yerkes said : 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 dis- 

 cover the characteristics of any habits which appear; (c) to enumerate 

 and evaluate the various external and internal influences on habit-forma- 

 tion; (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, Allolohophora foetida, 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 arti- 

 ficial 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 (6) 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 5 to 20. The 

 5-trial series were found, on the whole, more satisfactory. 



Eeferring now exclusively to the results obtained for a single worm 

 which has been under observation since October, 1911, the following re- 

 sults may be presented : (1) Allolohophora is capable of acquiring certain 

 definite modes of reaction. (2) Modifications appear as the result of 

 from 20 to 100 experiences. (3) The behavior is extremely variable be- 

 cause of variations in external conditions and in the condition of the 

 worm itself. (4) There is a tendency to follow the mucous path through 

 the apparatus, but this is not sufficiently strong or constant to yield per- 

 fect results. (5) The following are the chief modifications which have 



