356 BOTANICAL GAZETTE [ NovEMBER 
The memoir is too voluminous to permit an adequate summary in the 
space at command, and the original should be available in every laboratory 
where research is prosecuted. Devaux gives a résumé of his work in the 
final chapter, from which some extracts are here made, 
Lenticels are found in all the great groups of vascular plants and on all 
their organs which have secondary growth. The primary number on the 
stem is in ratio with the vigor of growth (indicated by the length of shoots or 
internodes), with the total number of internodes, and with the numerical fank 
of each internode. The curve of their production agrees closely with the 
curve of elongation of the internode, though the maxima do not exactly 
coincide. In each internode the lenticels are almost always more numerous 
on the distal moiety. The dimensions attained by lenticels depends directly 
on their number per unit of surface. 
Two types are distinguished: (1) the closing layers are few in number, 
consisting of cells intimately united, with no (or small) intercellular spaces, 
being oftentimes comparable to true cork; (2) the closing layers are numer- 
ous, composed of rounded cells with many large intercellular spaces, and are 
like the packing cells (Fwd/zellen ; cellules comblantes), but suberized. The 
packing cells are alike in both. 
As to origin, lenticels are primary or secondary. Primary 
formed early and at points determined by an organ (stoma, rootlet, less 
often a bud). Secondary lenticels are formed later and at points not deter- 
mined by an organ. Whenever stomata are present there is a tendency t 
produce lenticels below them, usually in the cortex, sometimes in the per 
cycle. If stomata are very numerous, partial or complete abortion of net 
lenticels may occur. Some stems, wanting stomata, produce lenticels late, 
in the neighborhood of a bud after the fall of the leaf. 
lenticels are 
destruction to death or suberization of the cells. 
ation produces complete rupture of the closing layers, 
spring, followed by hypertrophy, death, or suberization (accompan™ a 
by sclerosis), and by centripetal displacement of the cambium or 18 | 
Boe r level. 
formation into permanent tissue, to be regenerated later at a deepe singe 
times a complete 
. osit¥ 
ae is 
occurs, not in winter only but throughout the year. Thanks to th ee 
they certainly serve in large measure in the general gascom 
the organs. But it would be false to say that the lenticels exist she pls 
exchanges. For (1) they are often absent or insufficient; (2) EF of the 
has porose regions different from lenticels; (3) open! eee af 
lenticels is not due to the needs of aeration. Rather they os och 
transpiration and automatic regulators of the internal moisture, ae 
