1913] CHAMBERLAIN—MACROZAMIA MOOREI 153 
has occurred only at the periphery, the vacuole having been formed 
by the breaking down of free nuclear material, are questions which 
could be answered by a glance at material in the desired stages. 
The extensively segmented proembryos of Macrozamia and Cycas, 
and even the temporarily segmented proembryo of Dioon, are, in 
our opinion, more primitive than the proembryos of Zamia and 
Ceratozamia, which are segmented only at the base. 
At the stage shown diagrammatically in fig. 9 and quite accu- 
rately in fig. 11, the differentiation into suspensor and embryo proper 
is quite distinct, but there is not yet any differentiation of plerome 
and periblem or even dermatogen; the outer layer of large absorbing 
cells still showing numerous periclinal divisions. 
Unfortunately, the young leaves of Macrozamia contain a poison 
which causes a kind of paralysis in cattle, and consequently the 
plant is in bad repute among cattlemen. At Springsure, the only 
habitat mentioned for M. Moorei, the plant is being exterminated so 
rapidly that in a few years it may be hard to find a specimen. In 
killing the plant, a notch is chopped in the trunk and a large hole 
is then bored from the notch to the center of the pith (fig. 12). 
The hole is filled with arsenic and the plant soon dies.. The dead 
specimens become quite brittle and are soon broken down by the 
wind. The notch and the characteristic appearance of a poisoned 
specimen are shown in fig. 12. The species is beautiful and grows 
rapidly, but it is almost never found in botanical gardens and con- 
servatories. It would be a pity to allow a plant with such good 
claims to the title of missing link to become extinct, in spite of 
the fact that it is easily accessible. 
Summary 
1. Macrozamia Moorei bears numerous lateral cones in the axils 
of leaves, in this respect being identical with the mesozoic Ben- 
nettitales. 
2. The pollen grain, at the time of shedding, contains a persist- 
ent prothallial cell, a generative cell, and a tube cell; the exine does 
not cover the apical part of the grain. In the young pollen tube 
the generative cell has given rise to a stalk cell and a body cell like 
those of other cycads. 
