336 The American Naturalist. [Apa 
lution of which scientific travelers have addressed themselves. 
Michaux made a careful study of the Cypresses, and in his ‘‘ Sylva,” 
published in 1819, says: ‘‘ The roots are charged with protuberances 
eighteen to twenty-four inches high. These protuberances are always 
hollow, and smooth on the surface, and are covered with a reddish 
bark, like the roots, which they resemble in softness of wood. They 
exhibit no sign of vegetation, and I have never succeeded in obtaining 
shoots by wounding the surface and covering it with earth. They are 
peculiar to the Cypress, and begin to appear when it is twenty to 
twenty-five feet high.” Michaux adds, with the frankness natural to a 
scientific mind, ‘‘No cause can be assigned for their existence.” 
Hoopes says in his ‘‘ Book of Evergreens’’ (1868): ‘‘ No apparent 
function for which the knees are adapted has been ascertained.’’ And 
Veitch, who seems to have studied the protuberances in England, gives 
in his “‘ Manual ” (1881, p. 216) a picture of a tree growing at Iles- 
worth, surrounded by scores of .knees, and says: ‘‘ They are peculiar 
to this Cypress, and no cause has been assigned for their existence.’ 
That the question continued in this unilluminated condition until 
recently was shown in 1882, when I had the privilege of visiting, in 
company with the highest botanical authorities,—Dr. Gray, Thomas 
Meehan, John H. Redfield, John Ball, Professor Carruthers and others, 
—the classic collection of trees planted by William Bartram on the bor- 
ders of the Schuylkill. There we examined a fine Cypress and the 
knees it had produced. Dr. Gray then told me that the use to the 
tree of the knees was unknown. I remarked that they might be a 
means of raising a point on the root above surrounding water to the 
end that a leaf-bearing shoot could readily sprout therefrom, To this — 2 
hd 
suggestion he made the same statement made by Michaux and above 
recorded. Unaware that the subject had been so thoroughly investi- 
gated, I have since that period examined hundreds of living “‘ knees”? 
in southern swamps, and found upon them no trace of bud, leaf or 
sprout, except where some seed may have lodged in a decayed or de- 
pressed portion of the surface and there taken root. 
In 1887 I had the good fortune to find a number of Cypress trees un- 
der such unusual conditions that their aforetime subterranean anatomy 
could be studied without obstruction, and I reached a conclusion re- 
specting the use to the treé of the protuberances which I have retained 
in my note-book, awaiting an opportunity to make some further illus- 
3I have ridden among them in central Florida, in temporarily dry upland basins, pig 
they arose to my breast as I sat upon the saddle, and were not less than seven feet 
height above the root. : 

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