786 The American Naturalist. [September, 
Some writer whom I ha\e read often, Prof. G. K. Gilbert I think, 
said (in substance) he always Hked to have all the steps, pro- 
cesses and observations b>- and from which an investigator has 
arrived at his conclusions. I like this myself, and shall, at the 
risk of being tedious to the reader, give my observations, impres- 
sions, conclusions, changes of opinion, disappointments, etc. Up 
to and for several years after 1872 1 accepted the teachings of 
the books on Dynamic Geology with childish confidence. I 
supposed the surface, gravel-less clay was the sedimentation of a 
still lake. That year (1872) I had occasion to cut down a sugar 
maple tree in what is now the fair ground at Rockville, Indiana. 
The tree was about twent>- inches in diameter at the stump. 
When it fell, the stump was so nearly sound that I did not notice 
a very small decay in the heart. I cut off eight feet of butt, and 
.split it into quarters. It split as easy and straight as pine. When 
I halved it, I found a long, cigar-shaped, rotten heart, six feet long, 
by about six inches diameter. The centre of this rotten place 
was as perfect yellow clay as I e\'er saw. The fine grit could be 
casil)' detected by the teeth. Following it from the centre to the 
sides and toward the ends, the clay gradually changed to wet, 
soft, rotten wood. There was no distinct line where the clay 
ended and the rotten wood began. This was a curicxsity to me, 
and I kept the sample several >-ears. There was no hole in the 
body of the tree where an>- insect could then carry the clay in, 
and I doubt if there ever had been a hole grown over and closed 
o\'er b\- concentric growths of the tree. I showed this to many 
people and told it to many more, and among the number to my 
teacher. Prof B. C. Hobbs (Ex-Supt. Pub. Inst. Ind.). Being a 
Quaker he replied thus: "Thou hast not carefully observed it. A 
crawfish working up from below happened to strike the hollow of 
the tree, and kept hunting upwards for the surface of the mound, 
and thus filled the cavity of the tree with clay." A few days later 
I took my axe and visited the stump. The decay at the heart 
on the top was so small I could not put my fingers in it; but I 
cut the stump off a foot lower, and there it was entirely solid and 
sound. How came that clay to be sealed up in that tree? was the 
quer>^ I then kept a watch out for all rotten logs and stumps 
