1913] Gee: Behavior of Leeches VJd 



A. THE GENERAL REACTIONS OP THE LEECHES DINA 



MICROSTOMA MOORE AND GLOSSIPHONIA 



STAGNALIS LINNAEUS 



I. INTRODUCTION 



The work reviewed in this paper is the outgrowth of studies 

 begun on the modifiability of behavior of leeches. Upon under- 

 taking this problem the writer was impressed with the lack of 

 work on the general reactions of the forms he wished to investi- 

 gate. This deficiency was the stimulus productive of the general 

 studies presented in the first part of this paper. A knowledge 

 of the responses of the leeches made more efficient a detailed 

 investigation of certain features of the modifiability of behavior 

 of one of the species studied, Dina microstoma Moore. The 

 second part of the paper is a consideration of the results of this 

 investigation. 



My chief debt of gratitude is to Professor S. J. Holmes for 

 suggesting the problem, and for constant advice, criticism, and 

 encouragement during the progress of the work. To Professor 

 C. A. Kofoid I wish to acknowledge my appreciation of many 

 courtesies extended. The identification of the material used was 

 made by Professor J. Percy Moore of the University of Penn- 

 sylvania, and to him I desire to express my appreciation of the 

 favor. 



II. RESUMfi OF LITERATURE 



The contributions to leech literature are enormous in quantity 

 and extend back to the middle ages. The interest in leeches 

 manifested in this literature is very largely the outgrowth of the 

 important part played by the blood-leech in early medical prac- 

 tice. That the estimated value of the animal was very much out 

 of proportion to its real value is a fact too obvious for mention. 

 In spite of the recognized fact that the leech is an agent for 

 the transfer of blood parasites from one host to another, there 

 still persists in the medical practice of today a use, fortunately 

 diminishing, of the blood-leech. 



