Horse and Man, 
357 
stant use, or the slow cumulative process of natural 
selection, has served to develop a keenness of sense 
almost preternatural. The vulture’s eye, with all the 
advantage derived from the vulture’s vast elevation 
above the scene surveyed, is not so far-reaching as 
the sense of smell in the pampa horse. A common 
phenomenon on the pampas is a sudden migration 
of the horses of a district to some distant place. 
This occurs in seasons of drought, when grass or 
water fails. The horses migrate to some district 
where, from showers having fallen or other circum- 
stances, there is a better supply of food and drink. 
A slight breeze blowing from the more favoured 
region, which may be forty or fifty miles away, or 
even much further, is enough to start them off. Yet, 
during the scorching days of midsummer, very little 
moisture or smell of grass can possibly reach them 
from such a distance. 
Another phenomenon, even more striking, is 
familiar to every frontiersman. For some reason, 
the gaucho horse manifests the greatest terror at an 
Indian invasion. No doubt his fear is, in part at 
any rate, an associate feeling, the coming of the 
Indians being always a time of excitement and com- 
motion, sweeping like a great wave over the country ; 
houses are in flames, families flying, cattle being 
driven at frantic speed to places of greater safety. 
Be this as it may, long before the marauders reach 
the settlement (often when they are still a whole 
day’s journey from it) the horses take the alarm 
and come wildly flying in : the contagion quickly 
spreads to the horned cattle, and a general stampede 
ensues. The gauchos maintain that the horses smell 
