42 ME. SWALE VINCENT ON THE 



in structure and origin, and being inclined to the opinion that these bodies are 

 homologous throughout Vertebrates, I considered that a careful enquiry into their 

 anatomy and histology in the lowest class of Vertebrates could not fail to be of some 

 value as a contribution to our knowledge of their exact distribution and relationships. 



Moreover, I felt that there was definite need for such an enquiry and clear 

 statements of its results. Although some good work has been clone upon the subject, 

 it is embodied only in scattered, often antiquated and inaccessible memoirs ; the 

 text-books scarcely refer to the subject, and various writers who mention the supra- 

 renals make serious errors as to points of fact. 



Some authors have attempted to establish the view that (in Teleosts), where 

 suprarenals are present, there is no lymphatic head-kidney, and vice versa ; in other 

 words, that the suprarenals are interchangeable with the head-kidney, that where one 

 exists the other does not. I shall be able to show that this idea is quite groundless. 



Again, certain writers appear to think that suprarenals are comparatively rare 

 objects among the Teleosts. It will be seen that, so far as my observations have gone, 

 they are universally present in this order. I will not enlarge further on these points 

 here, as they will be dealt with in detail in the body of the paper. 



As for methods of work, these have been very various. I have examined fifty-five 

 species in all, and many individuals of several species. Most of these have been 

 perfectly fresh, indeed all but nine, which v>ere preserved specimens. 



In each case I have observed in situ the position and relations of the suprarenals 

 and the head-kidney. After careful removal, both these have been examined 

 microscopically. Numerous sections of various parts of different kidneys have also 

 been made and examined. 



Some preparations were made quite fresh, i. e. sections cut with Swift's " Ether 

 Freezing Microtome." Others have been hardened in alcohol or Midler's fluid, 

 stained in bulk, imbedded in paraffin, and cut with the " Eocking Microtome." The 

 precise method I have used to the greatest extent is the following : — 



The material is hardened in Midler's fluid in the usual way for about six weeks. 

 [In some cases the process has been hastened by keeping the tissue at a temperature of 

 about 36° C] It is then double-stained in bulk with Ehrlich's hsematoxylin and 

 eosin, and imbedded in paraffin. 



In working at the naked-eye anatomy in the Elasmobranchii, I have made use of 

 both the chromic-acid method of Semper and the osmic-acid method of Chevrel. 



I have made a special point of obtaining, in all cases where this was possible, 

 perfectly fresh specimens, and no results, with one or two exceptions, have been 

 considered worth recording, especially in a histological direction, unless the tissues 

 were practically living at the time of dissection. 



I was convinced that what was particularly needed was a series of accurate drawings 

 of the suprarenal bodies and their relation to the kidney. Consequently I have given 



