74 THROUGH THE BRAZILIAN WILDERNESS 



Often in crossing bayous and ponds the water rose almost 

 to their backs; but they splashed and waded and if nec- 

 essary swam through. The dogs were a wild-looking set. 

 Some were of distinctly wolfish appearance. These, we 

 were assured, were descended in part from the big red 

 wolf of the neighborhood, a tall, lank animal, with much 

 smaller teeth than a big northern wolf. The domestic dog 

 is undoubtedly descended from at least a dozen different 

 species of wild dogs, wolves, and jackals, some of them 

 probably belonging to what we style different genera. 

 The degree of fecundity or lack of fecundity between dif- 

 ferent species varies in extraordinary and inexplicable fash- 

 ion in different families of mammals. In the horse family, 

 for instance, the species are not fertile inter se; whereas 

 among the oxen, species seemingly at least as widely sep- 

 arated as the horse, ass, and zebra species such as the 

 domestic ox, bison, yak, and gaur breed freely together 

 and their offspring are fertile; the lion and tiger also breed 

 together, and produce offspring which will breed with either 

 parent stock; and tame dogs in different quarters of the 

 world, although all of them fertile inter se, are in many 

 cases obviously blood kin to the neighboring wild, wolf-like 

 or jackal-like creatures which are specifically, and possibly 

 even generically, distinct from one another. The big red 

 wolf of the South American plains is not closely related to 

 the northern wolves; and it was to me unexpected to find 

 it interbreeding with ordinary domestic dogs. 



In the evenings after dinner we sat in the bare ranch 

 dining-room, or out under the trees in the hot darkness, 

 and talked of many things: natural history with the na- 

 turalists, and all kinds of other subjects both with them 



