1897.] 
8 
The Bacterial Diseases of Plants: 127 
half full of sterilized water. From these second dilu- 
tions, the inoculations were made. The bacteria were 
isolated by the poured plate method, dextrose-pep- 
tone, nutrient gelatine being first used as asubstratum, 
and subsequently nutrient glycerine agar which 
proved very satisfactory. - 
Yes. The method of infection was as follows. The 
bacillus was first cultivated in a variety of fluid media 
until a suitable one was found. A watery potato 
juice with the addition of 1-2 per cent dextrose was 
finally selected as most suitable, the bacillus develop- 
ing better in this than in any other medium. This 
broth was made as follows: Fresh potatoes were 
reduced to pulp and digested for some hours in cold 
water. The fluid was then filtered out and the dex- 
trose added. The filtrate was then boiled, filtered 
again, and finally sterilized in the ordinary way 
under cotton plugs. A series of glass dishes (Präpar- 
atengläsern), about 8 cm. deep and 10 cm. broad, were 
filled half full of this broth. These dishes were closed 
by corks having a short, cotton-plugged glass tube 
passing through them. The vessels with the enclosed 
nutrient fluid were then sterilized by discontinuous 
heat. The potatoes to be tested were selected with 
great care, and their surface was sterilized as far as 
practicable in the following manner. These living 
tubers were first cleaned mechanically, then plunged 
for some minutes into a solution or mercuric chloride, 
and finally washed repeatedly in sterilized, distilled 
water. In this way some of the tubers (not all of 
them) were rendered completely sterile. The tubers 
were then placed in the sterilized broth in the glass. 
dishes, the mass of the fluid having been so chosen 
that when the sterilized tubers were in place they 
were entirely covered by the broth. The fluid was 
then inoculated with small quantities of the bacilli, 
derived from pure cultures, by removing the cotton 
plug from the glass tube for a moment and inserting 
