Then he led us to a little pond in the midst of the forest where the night heron sometimes nested. A pair of them had nested there in a big water maple the year before, but the crows had broken them up. As we reached the spot the cry of the heron was heard over the tree-tops. "That is its alarm note," said the President. I remarked that it was much like the cry of the little green heron. "Yes, it is, but if we wait here till the heron returns, and we are not discovered, you would hear his other more characteristic call, a hoarse quawk." Presently we moved on along another path through the woods toward the house. A large, wide-spreading oak attracted my attention--a superb tree. "You see by the branching of that oak," said the President, "that when it grew up this wood was an open field and maybe under the plough; it is only in fields that oaks take that form." I knew it was true, but my mind did not take in the fact when I first saw the tree. His mind acts with wonderful swiftness and completeness, as I had abundant proof that day. [Illustration: A BIT OF WOODLAND ON THE SLOPE TOWARDS OYSTER BAY From stereograph, copyright 1907, by Underwood & Underwood, New York] As we walked along we discussed many questions, all bearing directly or indirectly upon natural history. The conversation was perpetually interrupted by some bird-note in the trees about us which we would pause to identify--the President's ear, I thought, being the most alert of the three. Continuing the talk, he dwelt upon the inaccuracy of most persons' seeing, and upon the unreliability as natural history of most of the stories told by guides and hunters. Sometimes writers of repute were to be read with caution. He mentioned that excellent hunting book of Colonel Dodge's, in which are described two species of the puma, one in the West called the "mountain lion," very fierce and dangerous; the other called in the East the "panther,"--a harmless and cowardly animal. "Both the same species," said the President, "and almost identical in disposition." Nothing is harder than to convince a person that he has seen wrongly. The other day a doctor accosted me in the street of one of our inland towns to tell me of a strange bird he had seen; the bird was blood-red all over and was in some low bushes by the roadside. Of course I thought of our scarlet tanager, which was then just arriving. No, he knew that bird with black wings and tail; this bird had no black upon it, but every quill and feather was vivid scarlet. The doctor was very positive, so I had to tell him we had no such bird in our state. There was the summer redbird common in the Southern States, but this place is much beyond its northern limit, and, besides, this bird is not scarlet, but is of a dull red. Of course he had seen a tanager, but in the shade of the bushes the black of the wings and tail had escaped him.