REGENERATION IN ZAMIA. 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 
Joun M. CovutrtrerR and M. A. CHRYSLER. 
(WITH EIGHT FIGURES) 
Mr. P. H. Rotrs, in charge of the Subtropical Laboratory of the 
United States Department of Agriculture at Miami, Florida, first 
called our attention to the remarkable power exhibited by mutilated 
stems of Zamia floridana of producing new shoots and roots. This 
cycad grows in great abundance in the neighborhood of the station, and 
Rotrs stated that he had seen “portions (of the stem) not larger than 
an English walnut” produce both shoot and root. He was kind 
enough to send an abundant supply of this mutilated and sprouting 
material, collected about February 1, 1904. The pldnts grow at 
Miami in a pure and well-drained sand, with a soil temperature 
standing rather uniformly at about 30° C. On April 16 RoLFs 
reported that the temperature of the soil one inch below the surface 
was 40° C.; three inches below, 38° C.; and six inches below, 35° C. 
In most of the cases studied, the top of the thick stem had been 
cut off by the grubbing hoe, leaving the subterranean portion intact, 
though all of the smaller roots were lacking. Some of these stems 
were planted and observed at intervals. One of them, a plant about 
two years old, was placed in the greenhouse about February 13; the 
fully spread leaves soon withered, and no activity was visible for two 
and a half months, at the end of which time a new leaf was put forth 
from the bud. On June 1 the plant was removed carefully from the 
soil, its appearance being shown in fig. 2. The stem had been cut 
. off at x, and had produced a new apex. Since the last planting no 
ordinary roots had been produced, though an upwardly directed spur 
2™m long (not shown in the photograph) indicated the beginning of 
one of the characteristic apogeotropic roots; and yet the young shoot 
was in vigorous condition. 
An attempt was made to discover experimentally the possible 
; 452 [DECEMBER 
