Reprinted from THE AMERICAN JOURNAL OF PHYSIOLOGY, Vol. 43, No. 3, 



June, 1917 



CONTRIBUTIONS FROM THE BERMUDA BIOLOGICAL STATION FOR 



RESEARCH NO. 67 



RHEOTROPIC RESPONSES OF EPINEPHELUS STRIATUS 



BLOCK 



HOVEY JORDAN 

 Received for publication April 4, 1917 



CONTENTS 



I. Introduction 438 



A. The problem 438 



B. Review of literature 440 



II. Description of experiments 442 



A. Posterior and lateral orientation 442 



1. In groups of fishes 442 



2. In individual fishes 443 



B. Experiments on regional sensitivity 445 



C. Summary of normal rheotropism 446 



D. The end organs concerned in rheotropism 446 



1. Method of determination 446 



2. Observations and experiments 446 



a. Observations 446 



b. Experiments 448 



3. Summary of end-organ determination 452 



III. Discussion 452 



IV. Bibliography ' 454 



I. INTRODUCTION 



A. The problem 



The tropical fish known as hamlet or grouper (Epinephelus striatus 

 Bloch) is very favorable for biological experimentation. It is easily 

 obtained and is a hardy animal ; in response it is deliberate, but definite. 

 When considerable numbers of hamlets are held in confinement they 

 often manifest a tendency to crowd together closely, though without 

 any regular arrangement, their heads pointing in all directions. This 

 characteristic may have helped to give them the common name of 



"grouper." 



438 



