Soy 
Root Nodules in the Podocarpineae . 
trating the cell-walls of the host tissue, and where the zooglea thread comes 
in contact with the cell-wall it widens out somewhat before passing through 
into the neighbouring cell. Expansion in this area is characteristic of in- 
fection threads produced by Pseudomonas radicicola in leguminous nodules. 
In the interior of the host cell some of the Bacteria become isolated from 
the infection threads and divide independently, forming groups of organisms. 
The threads vary considerably in width, even in the same nodule, sometimes 
being only a single chain of organisms, at others, especially in Podocarpus , 
as many as five, six, or even more are arranged across side by side, so as to 
form apparently one thread. The Bacteria are quite evident in the cells 
when the sections are treated with Flemming’s triple stain or Heidenhain’s 
iron-haematoxylin. They also respond, in the manner described by 
Harrison and Barlow as being characteristic of Pseudomonas radicicola , 
to treatment with alcohol after Gram’s method of staining, that is, the 
aniline gentian violet is rapidly removed by ethyl alcohol, but not by amyl 
alcohol. 
The zooglea threads are undoubtedly analogous to those present in 
leguminous nodules, and like them they appear to have an affinity for the 
nucleus of the host cell. Shibata described the nuclei of the cortical cells 
of Podocarpus nodules, which he said contained mycorhizal hyphae, as 
assuming an amoeboid form, and subsequently dividing directly until 
as many as eight nuclei were present in a single cell. The nuclei appear to 
be stimulated to activity when they become surrounded by a large number 
of Bacteria, for many instances have been seen, especially in Podocarpus , 
where more than one nucleus has been present in the cell containing 
Bacteria. The increased number is evidently produced by amitosis, no 
karyokinetic figures having been observed in such cells, but numerous 
elongated nuclei, and others in which the elongated structure is constricted 
in the centre and about to form two nuclei (Fig. 15). This effect of the 
presence of Bacteria around the nucleus of the host cell is quite comparable 
with that seen in the root-nodules of Elaeagnus , where the nuclei have been 
described by the author as becoming amoeboid and very irregular in shape, 
and then in some cases disintegrating. 
As the season advances towards autumn further changes occur in the 
cortical cells of both root and nodules in all the genera. The cytoplasm 
and nuclei are gradually used up in the deposition of numerous cellulose 
bars on the walls of the cells, which gives them a scalariformly striated 
appearance, and assists in keeping them distended. The Bacteria tend to 
migrate from these cells, which appear first in isolated positions and thus 
become quite devoid of living contents. Gradually, however, almost the 
whole of the parenchymatous cortex, except the two or three outermost 
layers, becomes transformed into this water-storage tissue, and here the 
Bacteria continue to live in a quiescent state through the winter, until 
