224 
HAROLD’S DISCUSSIONS. 
only can detect them. Two apples that look exactly 
alike are recognized as different varieties. Yoorhelm, 
the Dutch gardener, cultivated twelve hundred vari¬ 
eties of tulips. He was able to distinguish the vari¬ 
ety from the bulb alone. 
Animals, too, vary greatly. I have heard that a 
shepherd is able to distinguish the sheep in his flock of 
several hundred, though the inexperienced can hardly 
discover any marks whereby he may know one from 
the other. Pigeons have been studied with much pa¬ 
tience, and no two of them are exactly alike. The 
fancier can easily pick out any particular one. Twins 
often can be distinguished only by their mother. If 
our observations were sufficiently accurate, we should 
be able to discover many marks of recognition where 
now we think none exist. 
Hoticeable differences exist not only in the color 
and proportion of animals, but also in motion, habit, 
and odor. Mr. Thompson-Seton tells us the story of 
Wully, a “yaller dog,” who was trained to herd 
sheep. One day his master sent him after a supposed 
missing sheep; the dog, not being able to find it, 
continued the hunt all day. Meanwhile the shepherd 
was obliged to go on and deliver the herd at a distant 
point, leaving the dog. When the animal returned 
he traced his master to a ferry and crossed in search 
of him. As the scent had long become “ stale,” he 
was unable to trace the man. For two years the dog 
crossed and recrossed, smelling every pair of legs that 
came over the ferry. It was computed that during 
this time the dog had smelled six million legs. One 
