804 Spratt . — The Formation and Physiological Significance of 
water, then crushed on a slide, and the material so obtained allowed to 
dry. This was then stained with Ziel’s carbol fuchsin or aniline gentian 
violet, and subsequent microscopical examination revealed the presence of 
numerous small rod-shaped Bacteria. These organisms were apparently 
identical with the Pseudomonas radicicola found in the root nodules of 
leguminous plants and also the Cycadaceae, Elaeagnaceae, Alnus , and 
Myrica. Many of them contained two or three minute, spherical, densely 
staining bodies, which are so characteristic of that organism. 
For further investigation with regard to the nature and growth of this 
organism, the exterior of some nodules from the Podocarpus roots was 
sterilized by placing them for about two minutes in a sterilizing fluid of the 
following composition : 
2*5 c.c. concentrated hydrochloric acid, 
i grm. mercuric chloride, 
500 c.c. water. 
They were then removed and thoroughly washed in distilled water, pre- 
cautions being taken that all the instruments used were quite sterile. The 
nodules were then crushed, and their contents placed in a nutrient medium 
of the following composition : 
1 grm. saccharose or glucose, 
0-5 grm. acid potassium phosphate, 
0-02 grm. magnesium sulphate, 
o-i grm. calcium carbonate, 
100 c.c. distilled water., 
The solution was then incubated at a temperature of 28° C. for two days, at 
the end of which period it had become quite cloudy owing to the rapid 
development of the rod-shaped Bacteria. 
Pure cultures of this organism were also obtained on solid media, pre- 
pared by adding 2 per cent, agar-agar to the above nutrient solution. 
The colonies produced, after two days’ incubation at 28° C., were ovoid to 
circular in shape, entire, raised, shining, and viscous, with a diameter of 075 
to 1 mm. They were apparently characteristic colonies of P seudomonas 
radicicola . 
Since this organism so closely resembled, in its appearance and growth 
on nutrient media, species obtained from the nodules of legumes and the 
non-leguminous plants mentioned above, which are known to assimilate 
atmospheric nitrogen, 100 c.c. of the above nutrient solution containing 
saccharose was placed in each of four Erlenmeyer flasks, 300 c.c. capacity. 
To two of them, the controls, was added 2 c.c. of a liquid culture of the 
organism, obtained, as described above, from Podocarpus nodules. All the 
flasks were then sterilized by autoclaving, at a temperature of J 40° C. and 
