72 Report OF THE BACTERIOLOGIST OF THE 
Attention should be called to the fact that in these tests we did 
not determine the number of germs which survived in any case 
but merely the fact that P. campestris was alive in certain tubes. 
A quantitative determination would have been desirable but in 
the nature of the case was difficult. The germs became so closely 
attached to the seeds in the long drying that when the seeds were 
placed directly into the agar the germs could not be dislodged 
by shaking and later produced a confused growth around the 
imbedded seeds. Grinding of the seeds was attempted but their 
texture was such that they were not reduced to sufficiently fine 
particles and the resulting growth was largely in clumps sur- 
rounding the fragments of seeds. 
We did not think it desirable to sterilize the seeds before apply- 
ing the cultures of P. campestris as such treatment would 
probably leave the surface of the seed in an abnormal condition 
and vitiate the experiment. Accordingly, the growths around 
the seeds were often a mixture in which P. campestris was com- 
pelled to struggle for existence and from which it must be isolated 
by sub-cultures. An earlier attempt to determine the vitality of 
P. campestris on cabbage seed failed because we added the seed 
to be tested to the agar without previous soaking. 
A positive result in this experiment indicates with certainty 
that P. campestris was alive upon the seed but a negative result 
does not make it certain that they were all dead. On practically 
all of the seeds there were gerins present other than P. campestris. 
In some cases these germs found the watery solution to which 
they were exposed some hours so satisfactory that they developed 
rapidly and overran the resulting cultures so completely that a 
recognition of P. campestris would have been impossible even 
though it had been present in moderate numbers. 
PATHOGENICITY OF GERMS ISOLATED FROM CABBAGE SEED. 
The ability to produce disease is a function of germs which is 
most readily affected by unfavorable conditions. It would not 
have been surprising if the P. campestris which had remained 
over winter on the dry cabbage seed were so weakened by this 
exposure as to be incapable of attacking the tissue of healthy 
cabbage plants. 
Cultures of the germs which had been found on the seed at the 
various examinations were preserved and on March 25, 1904, the 
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