366 Field, Forest, and Wayside Flowers 
neath their bark a store of nourishment which will 
feed the tender foliage of spring when it first be- 
gins to grow. 
The leaves now fading have not been suddenly 
slain by ruthless frost. For weeks they have been 
bringing to a peaceful and fitting close a life which 
reached its fulness in the dog-days. While as yet 
summer was at high tide nature began to form 
across each leaf-stalk, just at the point where it 
joined the main stem, a very thin layer of cork. 
The manufacture of cork is not a trust in posses- 
sion of the Spanish branch of the oak family. 
Cork is a constituent in the bark of most native 
flowering-shrubs and trees. It is also used by vege- 
tation in repairing its rents and healing its wounds, 
and sometimes a layer of it is interposed to isolate 
diseased or dying tissues and, as it were, quarantine 
them from healthy and growing ones. The 
** wound-cork’’ which the trees use in lieu of court- 
plaster may be covered by the subsequent growth 
of trunk or branch, so that eventually it lies deep 
in the woody tissues. 
But wherever it is met with cork can be read- 
ily recognized under the microscope by the forms 
of the cells composing it. They are square or 
brick-shaped, with clear-cut angles, and they lie as 
