1913] CHAMBERLAIN—MACROZAMIA MOOREI 143 
known how often new crowns are produced. If crowns are pro- 
duced every year, a plant a meter in height might be considerably 
less than 100 years old. 
Although the trunk is so massive, a transverse section shows 
the large pith, scanty wood, and large cortex, so characteristic of 
cycad stems, there being no extensive development of wood like 
that found in large stems of Dioon spinulosum. A plant about 3 m. 
— 
Fic. 2—M. Moorei: transverse section of stem 45 cm. in diameter 
in height, with a stem 45 cm. in diameter, had a zone of xylem 
and phloem only 5 cm. in width (fig. 2). In the photograph 
three distinct regions are shown; the innermost is the xylem, the 
middle one its accompanying phloem, and the outermost a second 
cylinder with its xylem and phloem which show clearly in the 
material but which are not differentiated in the photograph. The 
trunk, therefore, is polyxylic. The outer cylinder evidently origi- 
nates in the cortex, as in Cycas, but is separated from the primary 
cylinder by only a scanty amount of parenchyma. There are 
