STUDIES IN THE RETINA. 443 



Studies in the Retina: Rods and Cones in the 

 Prog and in some other Amphibia. 



By 



H. m. Bernard, M.A.Cautab. 



(From the Biological Laboratories, Rojal College of Science, London.) 



VVitli Plates 30 and 3L 



Part II. ' 



The first part of this paper was devoted to showing that 

 the structures called " cones ^' in the amphibian retina were 

 the earlier stages in the development of the new rods required 

 by growth, and that they force their way in wherever there 

 is room for them between already existing rods. The forms 

 of these elements with the positions of their nuclei^ were alone 

 dealt with. In this paper it is proposed to give some account 

 of the intimate structure of the amphibian rod. The minute 

 details to be described will necessitate some discussion of the 

 physiological processes which, so far as I have been able to 

 interpret them, underlie their forms. 



Little success has so far attended the attempts of naturalists 

 to unravel the finer structure of the rods. Indeed, the sub- 

 ject seems to have been temporarily closed by the classical 

 researches of Max Schultze in the sixties, for since that 

 time little or no advance has been made. The earlier 



1 The final revision of this MS. was kindly undertaken by my friend Mr. 

 Martin Woodward, during my temporary absence from England. 



* Ou page 44 I inadvertently attributed to Borysiekiewitz an observation 

 of my own. This will be fully dealt, with in Part III. 



