Genito-nrinary Apparatus of the Male Porpoise. 113 



as observed by him do not at all points harmonise with our 

 observations, probably owing to different methods of preserva- 

 tion. However, since the use of Formal enables us to fix 

 organs in their relatively normal shapes and positions, the 

 results which we have obtained are of an extremely instruc- 

 tive nature. The procedure adopted in connection with the 

 process of preservation and fixation has already been described 

 in connection with our examination of the alimentary viscera. 



The study of the urinary organs of Cetacea is of extreme 

 interest, chiefly owing to the fact that, as marine mammals 

 whose habitat is exclusively aqueous, they are provided with 

 an integument which does not possess sweat-glands, and 

 therefore excretory products are eliminated either by the 

 respiratory or urinary organs. Intimately associated with 

 the excretion of water and watery vapour, there is the 

 further question of the available sources for the renewal of 

 this fluid. The sea-water in which these mammals live, and 

 the fluids within the bodies of the animals upon which they 

 feed, are both salt, and therefore they probably swallow a 

 quantity of saline matter quite out of proportion to that 

 assimilated by land mammals, while for most of them the 

 opportunity of access to sources of fresh-water may be 

 regarded as non-existent. 



If, therefore, Cetacea have no opportunity of imbibing 

 fresh- water, and if they require to relieve thirst (supposing 

 they experience this sensation), then not only must the 

 fluids within their bodies present a high degree of salinity, 

 but the processes of alimentation and the secretion of urine 

 must be correspondingly modified, and the structure of the 

 kidney might be expected to show arrangements for the 

 secretion of a fluid which must always be of high specific 

 gravity. In the paper above referred to we have already 

 shown that the structure of the alimentary canal, especially 

 towards its hinder end, suggested, in the presence of great 

 numbers of large mucous glands, the capability of preventing 

 the inspissation of the food residuum, and certainly the 

 alimentary canal contained no substance more dense than 

 thick cream. 



The Kidneys. — These organs were situated upon the dorsal 



