furnish elements of greater probability and determine search in that direction. To obtain an ideal curve for a uniform surface it would be necessary to liberate the pigeon on a Dakota prairie or in mid-ocean, where no break in the landscape is visible even from an altitude of a thousand feet. It is not, however, difficult 
Fig. 11.
Search-line of a shepherd dog.
+ Starting point. B. Bull. to find approximations to the ideal in the widening circles and the flights in different directions to be seen in Figs. 1 to 4.
It may seem to some that in denying a "sense of direction" and affirming a logic is like jumping from the frying pan into the fire. The only thing to be said on this point is that we do find evidence for search-logic and no evidence for "direction-sense." And further, in the one case we explain the phenomena by something fundamental in animal life, which we do know something about; whereas on "sense-direction" grounds we are explaining the partially known by the absolutely unknown.
An instance of quite a different sort from the above stood in the writer's mind as almost conclusive proof of sense-direction powers for a number of years. It may be briefly stated as follows:
A large Maltese tomcat once joined, on his own invitation, an evening rowing party on one of the Wisconsin lakes. It was a sultry summer night, as dark as a moonless night can be. Not a breath of air was stirring. We rowed nearly due north, straight out toward the middle of the lake, which is something over two miles wide. For some time Tom purred and made himself generally agreeable from one end of the boat to the other; but at last he grew restless and extremely anxious to get home. He would climb out to the end of the boat and, stretching his head toward home, mew almost continuously. We amused ourselves for some time by turning the boat slowly round and round, first one way then the other, to see if we could throw Tom off his bearings; but all to no effect. Whether right side, left side, bow or stern, Tom was always on the part of the boat nearest home, and straining as far as he could in that direction. Fully a mile from any shore, how could he tell which shore was which? But few lights were visible, the lake is thickly wooded, and the cottages stand well back among the trees. Not one in the party could recognize the lights of our own group of cottages. And no one but myself and cat had any idea which way to go for home. For my part, I had kept an eye out for the north star. But what
