270 SCIENCE PROGRESS 



Ridgeway seriously suggest that the absence of shoulder- 

 stripes in the Somali and Arabic asses is due to the effect of 

 the scorching Red Sea climate?) Again, we have Prof. 

 Galton's authority for the fact that zebras, however conspicuous 

 in the open plains by day, appear hardly visible at a short 

 distance at night — a fact that must seriously embarrass their 

 enemy the lion in his final assaults. Such striping would, on 

 the other hand, spell rapid extermination for the species in any 

 place inhabited by wolves. These carnivora do not, of course, 

 exist in Africa ; but before discussing the reasons for other 

 variations of colour such as in the quaggas there, one would 

 have to consider closely the habitat of the species concerned, the 

 methods of the carnivora that prey on it, and the times and 

 periods of its greatest peril. Thus, for instance, in the case 

 of asses their grey colour harmonises admirably with their 

 surroundings under the intense white light of the desert county 

 they inhabit. And in addition to the zebras already noted, the 

 example of the Burmese barking deer furnishes a warning 

 against hasty judgments by first appearances. Nothing can be 

 brighter or more conspicuous than the orange coat of this 

 animal when in a green field. Closer examination shows, 

 however, that it habitually lives in dense jungle, that when this 

 jungle sheds its leaves in the hot weather the deer's coat matches 

 fairly well with the dead foliage, and that at night, when its 

 enemies are on the prowl, it is indistinguishable at a short 

 distance. We may safely postulate similar explanations in 

 the case of the remaining Equidce. 



In addition to his remarks on colouring, Prof. Ridgeway lays 

 some weight on the physical changes known to have occurred 

 in horses in the Basuto Mountains, Java, and (he might have 

 added) in the Falkland Isles. But the horses originally intro- 

 duced into these localities must have been artificially bred 

 animals, and we all know how rapidly such varieties tend to 

 retrogress when exposed to conditions which do not favour 

 the qualities artificially developed. In none of these countries 

 would size or its concomitant speed confer any superiority ; in 

 fact, in mountains large horses are at a distinct disadvantage. 

 In such conditions the artificial qualities so laboriously obtained 

 quickly disappear, and the animal reverts to its ancestral type. 

 Man, it is needless to say, has never yet attempted to apply 

 to himself the methods by which he has differentiated and 



