APPENDIX B. 



REPORT on the Structuke of the Phosphorescent Organs of Fishes. By R. von 

 Lendenfeld, Ph.D., F.L.S., Assistant and Demonstrator in the Biological 

 Laboratory of University College, London. 



PREFACE. 



Most of the deep-sea fishes and also some pelagic surface fishes of nocturnal habits 

 collected during the voyage of H.M.S. Challenger, possess certain organs which appear 

 to have the function of producing light — in the case of deep-sea forms — to illuminate the 

 eternally dark abysses of the ocean. 



Dr. Giinther, whilst engaged in the examination of the fishes collected by H.M.S. 

 CJhallcnger, intrusted mc with the histological investigation of these organs in such speci- 

 mens as could be spared for this object, and the results of these researches will be found 

 in the following pages. It is my pleasant duty here to express my thanks to Dr. Giinther 

 for his great kindness in assisting me to bring these studies to a successful issue. 



Although the specimens examined by me are for the most part remarkably well 

 j)reserved, still the most minute histological details would have remained doubtful on some 

 points, if I had not had other material, specially preserved for histological purposes, 

 to compare with the Challenger specimens. Where it was necessary I have embodied 

 in this Report the descriptions of the structure of the phosphorescent organs in 

 such specimens. I must express my thanks to Professor Ray Lankester who placed 

 some excellent material for this work at my disposal, and in whose laboratory the 

 necessary series of sections were prepared. 



The phosphorescent organs were studied principally by means of series of section.-s, 

 cut in the usual manner after embedding in paraflin ; they were stained with Kleinen- 

 berg's hsematoxylin, borax-carmine, alum-carmine, or picrocarmine. The last named 

 produced the best results. 



