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180 BACTERIA IN RELATION TO PLANT DISEASES. 
plants which yielded no bacteria at this level were now cut off just above the roots and a third set of 
tubes inoculated from the inner tissues, all of which now yielded this organism. As this positive 
result was not in accord with the previous experiments and might perhaps be attributed to injury 
of- the roots during removal from the pots, the following experiment was undertaken. 
Beans were planted in a nutrient fluid consisting of: water 1000: potassium nitrate 0.5, potas- 
sium phosphate 0.2, magnesium sulphate o.2, ferrum sulphate 0.1. They grew well in this fluid and 
when about 20 cm. high a culture of Bact. pyocyaneum was added. ‘The roots of some of the plants 
were purposely injured, while the others remained sound. After some days cultures were made from 
the interior of the plants. These showed the presence of Bact. pyocyaneum in all the injured plants, 
and in none of the uninjured ones. 
Ellrodt’s conclusion, therefore, is that bacteria can not penetrate sound roots, but may 
enter through broken ones, and that since root-injuries are common occurrences in soil, 
it is not yet certain that pathogenic bacteria can not enter the plant from infected soils. 
Clauditz criticises Ellrodt for not telling in what tissues the bacteria occurred. Fur- 
thermore, inasmuch as he does not state that he washed or otherwise removed the bacteria 
from the surface of the plants, he may really have got his results from surface organisms, 
which were dragged into the tissues. Certainly, the surface of his plants, particularly the 
parts near the roots and consequently near the bacterial fluid, should have been flamed or 
otherwise disinfected. In the last mentioned experiment, however, he probably did not 
get his results from surface organisms because his checks were sterile. 
Clauditz (1904) made a series of experiments with the typhoid bacillus to learn whether 
infection through plants is possible and especially whether this organism can penetrate 
into the interior of plants. In certain respects his statements also are vague. 
Clauditz used the plants which are commonly eaten raw, viz., radish, cress, and lettuce. The 
soil was taken from the yard of the Hyg. Institute of the Royal University of Berlin. To imitate 
as nearly as possible the conditions of the soil in the sewage fields several glass tubes were thrust into 
the earth a depth of 8 cm., and 24-hour old bouillon cultures of the typhoid organism were poured 
into these tubes every other day. After 8 days, repeated attempts were made to recover the organism 
from the soil, but these failed in spite of renewed infections with a fresher isolation. ‘These cultures 
were made both from the surface and from 4 to 6 cm. down. 
He states that it is difficult to isolate the typhoid organism from the earth because in most 
cases this organism quickly perishes when brought into competition with the bacteria of the soil. 
Following Rullmann’s advice he mixed the infected soil with double its quantity of sterile bouillon 
and incubated at 37°, but always the soil organisms got the advantage and the typhoid bacillus was 
not to be recovered in this way. He then tried to accustom the typhoid organism to the soil bacteria 
in bouillon cultures by adding to sterile bouillon a loop of a 24-hour bouillon culture of B. typhosus 
and 2 loops of soil and exposing for 24 hours at 37° C. From this tube 3 loops were then transferred 
to a second tube which was incubated for the same time and at same temperature, and so on for 10 
tubes. After 5 days the typhoid organism was not demonstrable in the first tube, and not after 24 
hours in the second, while in all the others the results were negative. 
The strain isolated from the second tube was designated ‘“‘ Typhus Erde I.’’ With this a second 
series of 10 tubes was inoculated in the same way as before. ‘The results from this set of tubes were 
all positive, and even after a half year the typhoid organism was easily demonstrated in tube ro. 
Along with it were present a variety of other bacteria, Bacillus subtilis, Bact. fluorescens liquefaciens, 
cocci, etc. : 
A second set of soil inoculations was undertaken with this strain, ‘‘’'yphus Erde II,” the 
bouillon cultures being now poured into the soil after dilution with sterile distilled water. It was 
now easy to demonstrate the bacillus in the soil and a strain so isolated was called ‘‘ typhus Erde IIT.” 
The latter was now used for all the subsequent experiments. 
After the organism had been isolated from the soil and when the plants were 5 to 8 cm. high, 
they were cut off close to the earth with a sterile knife, washed one-half hour in sterile water, bruised 
in a sterile mortar with sterile bouillon and then incubated for 24 hours at 37° C. Streaks were then 
made on Drigalski-medium, one out of four being positive. The experiment was repeated with the 
precaution first to put the plants in a 1:100 solution of mercuric chloride (time not stated) and then 
wash them thoroughly in sterile water. All the tests were now negative. ‘To avoid the objection 
that the mercuric chloride may have penetrated the plants and killed the bacteria, the experiment 
was repeated, the surface of the plants being sterilized this time (so far as regarded B. typhosus) by 
