THE CAT. 261 



protective mimicry, but this must be accounted 

 for on other grounds." Even the main objec- 

 tion, and the one which I myself at iirst felt 

 to stand absolutely in the way of the protec- 

 tive hypothesis — viz., that such formidable ani- 

 mals as jaguar display in common with the 

 weaker cats many of the special habits and 

 peculiarities upon which the argument is built 

 — does not seem an insuperable difficulty when 

 we take a wide view of our ground and con- 

 sider the facts in the light of what we know 

 concerningr the general laws of evolution and 

 the history of the development of diverse mod- 

 ern species from common ancestral types. 



The habit of purring when pleased is uni- 

 versal among all the cat tribe, and we may 

 therefore conclude that it also is of enormous 

 antiquity. I have no opinion to offer as to 

 the origin of the habit or as to its usefulness 

 either in the wild or tame state. The sound 

 seems to be caused by a rapid and continu- 

 ous vibration of the vocal cords in the larynx, 

 and is maintained with little variation when 

 the air is passing both outwards and inwards. 

 It is almost always produced with the mouth 

 closed, and seems to proceed not only from 



