AVERAGE, MAXIMUM, 
BOTANICAL GAZETTE 
TABLE III 
THE THREE SPECIES 
[DECEMBER 
AND MINIMUM LENGTHS OF VESSEL SEGMENTS OF 
Species Average Maximum Minimum 
Platanus occidentalis ....... °.786mm.| o.889mm.}| o.718mm 
Platanus Wrightii......... ©.549 0.727 °.390 
Platanus racemosa ......... 0.677 ©.749 ©. 608 
WOOD FIBERS 
These elements form the ground mass of sycamore wood, and 
their walls are usually much thicker than those of other wood ele- 
ments. The fiber length does not differ very much for the three 
species. They are shortest in Platanus racemosa and longest in 
P. Wrightii, but the difference is so slight that it cannot be depended 
upon as a reliable distinguishing character. Table IV gives the 
average lengths of 100 measurements on each species. 
TABLE IV 
AVERAGE, MAXIMUM, AND MINIMUM LENGTHS OF FIBERS OF THE THREE 
SPECIES 
é Species Average Maximum Minimum 
Platanus occidentalis ....... 1.63 mm 2.02 mm. I.39 mm. 
Platanus Wrightii......... 1.69 2.02 1.47 
Pitas FRCEMUEE ios 2... ¥, a5 1.93 1.26 
TRACHEIDS 
The tracheids of sycamore wood (pls. XXXII-XXXIV, /, and 
fig. 1, E) are found usually adjacent to vessels. These elements, 
together with the wood parenchyma fibers, form more or less con- 
tinuous irregular lines throughout the masses of wood fibers, from 
which they may be distinguished by their thin walls. Tracheids 
take an intermediate position in respect to size and form between 
vessels and wood fibers, and in sycamore wood they often possess 
characters belonging to either one or the other of these two very 
dissimilar kinds of elements. About midway between these two 
extreme forms (the vessel and the fiber) is the more or less fixed form, 
