282 BOTANICAL GAZETTE. [ November, 
breaking in fissures and subsequent curling up, that not un- 
frequently the hairs from this tissue are seen along the 
smooth surface of the wing. This is shown in figure 11.a. 
As the autumn growth begins, several layers of narrow 
plate cells are formed entirely around the stem and it now 
takes its winter’s rest. In the following spring, the manner 
of growth seems to vary. In most stems examined the pro- 
cess was quite similar to that of Quercus, the entire zone of 
phellogen cells developing rapidly till the protecting band 
of thicker walled plate cells breaks at the fissures and the new 
growth forces outward the last year’s wings. This rarely, 
if ever, continued longer than till the third year; the growth 
of the three years’ stems, as well as many of the two years’, 
being as follows: As the girdle of plate cells breaks, the in- 
creased growth in circumference of the entire rind cells ap- 
pears to take place most rapidly in sections under the fissures, 
or between the wings of the first or second year's growth. 
The periderm cells are formed more or less uniformly, but 
the foundations are laid for new wings between those already 
formed. In this way six more wings are formed, and not 
many seasons after this, the stem assumes the ordinary 
ridged and furrowed appearance which is no longer described 
as winged. Thus the transition from wings to ordinary fur- 
rowed periderm takes place. This method of transition is 
carried still further in 
ACER MONSI ANUM L,. 
edges of these during their first year’s growth; that is the 
second year of the stem. (See fig. 14. 4.) The result of the 
repetition of this process is the formation of a periderm 
| LiquipAMBar SryractFiva L. 
The cork wings found on this tree have one striking igh 
culiarity which renders them an exception to all other cases 
