Root Nodules in the Podocarpineae. 803 
stele. In the material of Podocarpus obtained during the autumn and 
winter the surface of the nodules was always quite smooth, whilst in 
P. chilina , P. elongata , and P. Totara obtained in the spring the epidermal 
cells in a few nodules were growing out into hairs, and a few were covered 
with numerous fine non-septate hairs about the same length as the nodule. 
In P. alpina gathered in February a very large number of the nodules were 
clothed with a thick mantle of long hairs, some of which were quite three 
times as long as the nodules. The hairs were most abundant on nodules 
which were one year old, and which were, in many cases, attached to the 
roots in, or near, the regions where they themselves were producing root- 
hairs, but they were also sometimes present on the nodules, which were 
two, three, or even four years old. In Microcachrys tetragona the surface 
of the nodules was generally quite smooth (Fig. 8), but occasionally small 
protuberances from the surface cells were visible. In Dacrydium Franklini , 
Saxegothaea conspicua , and Phyllocladus trichomanoides the production of 
hairs, in the spring, is a constant feature of all nodules which have com- 
pletely emerged from the cortex of the root. It is, therefore, usually in the 
beginning of the second season’s growth that practically all the surface cells 
of the nodules are capable of growing out to produce hairs, which radiate 
in all directions from the nodule (Figs. 6 and 7). In Dacrydium they 
attain a length about equal to that of the nodule in many cases, but some- 
times they are longer ; in Saxegothaea a thick mass of relatively long 
hairs covers the nodules, whilst in Phyllocladtis they are very long and 
straggling. 
These hairs are evidently comparable to root-hairs ; they are non- 
septate structures produced by the epidermal cells of the nodules, which are 
themselves modified roots. Like other root-hairs they are produced abun- 
dantly in the spring, whilst later in the year, in the autumn and winter, 
they collapse and eventually disappear. Any nodule which has reached 
maturity seems to be capable of producing these structures, but since they 
persist for very varying periods of time, nodules of diverse ages may be 
seen to possess hairs on their surface. When the nodule is more than two 
years old, however, they can distinctly be seen to be portions of the old 
hairs, which have remained attached to the nodules. They are evidently 
produced in response to certain environmental conditions in Podocarpiis and 
Microcachrys , where it is only some of the nodules which produce these 
outgrowths, but in Dacrydium , Saxegothaea , and Phyllocladus there is a much 
greater tendency for the formation of hairs, their presence in the spring 
being characteristic of these genera. The frequent presence of root-hairs, 
not only on the roots but also on the nodules in all the genera of the Podo- 
carpineae, precludes their association with a mycorhizal fungus. 
In order to ascertain whether there were any Bacteria present in the 
nodules, some were removed from the roots, carefully washed with distilled 
3 G 2 
