So Sg ae ie) ee a PEED GAN ae aed ee ne RE Car) teas tee eRe Pee ORY tf ee ie ee 
; rs SORE ote aar tere Pils Bi ced) EO iran ae 
? 5 aoe 
1913] CHAMBERLAIN—MACROZAMIA MOOREI 149 
as in Bennettitales; while in other species of Macrozamia and in 
Encephalartos the lateral cones are present but not so numerous. 
In a reduction from numerous lateral cones to a single cone, the 
natural limit would be the single terminal cone developed from the 
apical meristem, and with the transformation of the apical meri- 
stem into a cone, the formation of a cone dome in the pith would be 
a necessary consequence. Accordingly, the absence of cone domes 
from Macrozamia and Encephalartos is easily understood. 
Macrozamia Moorei, in its numerous lateral cones and in their 
mode of occurrence, presents a condition identical with that found 
in Cycadeoidea among the Bennettitales. As far as the mode of 
bearing cones is concerned, Macrozamia Moorei makes the transition 
from Bennettitales, like Cycadeoidea, to the modern cycads an easy 
one. In the structure of the individual cone, the transition is not 
so easy, but may become less difficult when more is known about 
the cones of the Bennettitales, especially the lower Bennettitales. 
The connection between the higher Bennettitales and the Cycadales, 
already a close one, is made still closer by M. Moorei, so that it 
might be doubted whether the differences are great enough to 
distinguish orders. 
The male gametophyte 
The pollen grain at the time of shedding contains three cells, a 
persistent prothallial cell, a generative cell, and a tube cell (fig. 6). 
As pollen shaken out from the cone loses a little moisture, it begins 
to collapse so that in a vertical view the grains appear elliptical, 
with a long narrow area at the top which does not stain when 
safranin is added (fig. 7). This elongated area becomes narrower 
as the grain dries and finally the sides come into contact. A study 
of sections shows that this elongated area at the top of the grain is 
not covered by the exine, but only by the intine, a situation which 
is constant in Ginkgo, but which has not been noted in cycads. 
Just beneath the portion not covered by exine there is usually a 
funnel-shaped depression. The cytoplasm of the pollen grain is 
quite dense and contains starch. 
The pollen from which figs. 6 and 7 were drawn was shaken from 
a cone in the Botanic Gardens at Sydney on November 3, 1911, 
