- nection was traced, the vascu- 
lar elements forming a hollow leaf; p, periderm; v, vascular cylinder. X 4. 
Tio] “COULTER & CHRYSLER—REGENERATION IN ZAMIA gs 
Mine the formation of a complete new structure in the one case, and 
the restoration of the” lost part of the old structure in another case 
may not be clear, but it is entirely probable that the central cylinder is 
more apt to be restored in young plants. ; 
The origin of the new roots is just as variable. It is customary 
tothink of secondary roots as 
arising from vascular tissue, 
and this was found to be true 
in several of the cases studied. 
In the case illustrated by 
Wg. 4, however, no trace of 
central cylinder was found, 
the piece of stem from which 
the shoot springs on one side 
and the root on the opposite 
Side being simply a chip from 
© cortex of an old stem. 
Between this shoot and root 
of cortical origin a distinct 
and complete vascular con- 
Fic. 3.—Median vertical section through 
apex of stem represented in fig. 2: /, base_of 
ylinder tapering at the ends Bie 
& 5). It seems certain that the decay of the “chip” in this 
Case would uncover a completely organized new plant. In any 
“vent, from this isolated cortex new organs and new kinds of 
issue have been formed, the new shoot arising from the outer edge 
Of the Cortex in the region of the cork cambium, and the root arising 
_ ‘Tom a more internal region of cortex. Whether the starting of > 
shoot determined the root, or vice versa, or neither, are matters 0 
onjecture, but a completely organized and independent new plant 
S been derived from isolated and relatively old cortical tissue. 
The attempt was made to determine the exact layer or tissue from 
Much the new shoots proceed. It seems evident that regions of 
Meri i to 4 i ither 
meristematic tissue alone are concerned, that is tissue which has eit 
= med so or has resumed its power of cell-division; and in a 
rdinary cycadean stem there are at least three such active reg) 
