224 The Celery-Rot Bacillus 



practised in lieu of " earthing-up, " tends to protect them not only from 

 mechanical injury caused by the chafing action of the soil particles 

 but also from the attacks of snails and slugs which are frequently 

 found gnawing the petioles. These animals might not only carry the 

 soft-rot organism from one plant to another but would produce the 

 wound necessary for the bacillus to gain access to the parenchyma 

 cells. That phytophagous creatures spread infection by transferring 

 pathogenic germs from plant to plant is inferred by Johnson and Adams 

 in their paper on Bacterial Rot in Turnips (14) where they say that 

 "so far as at present known, the disease gains entrance into the 'bulb' 

 through wounds caused by slugs or grubs living underground." 

 Erwin Smith (37) by actual experiment obtained infections by allowing 

 snails {Agriolimax agrestis) taken from plants affected by Pseudomonas 

 campestris to gnaw healthy plants, the snails being left in contact 

 with the latter for one night only. 



II. The Action of Antiseptics. 



Nutrient Bouillon as Culture Medium. Tubes of nutrient bouillon 

 containing antiseptics were inoculated from pure cultures and examined 

 from day to day for signs of growth as indicated by the development 

 of turbidity in the medium, followed by sedimentation. 



Method. 9 c.c. of peptonized bouillon (+ 10 Fuller's scale) were 

 run into each of a number of test tubes which were then plugged and 

 sterilized. To each was then added 1 c.c. of the antiseptic in sufficient 

 concentration to produce the required percentage in the 10 c.c. now 

 contained in the tube. The "stock" solutions of the various sub- 

 stances used were made up in stoppered bottles several hours previous 

 to their use so that the probability is that they were quite sterile when 

 the dilutions were prepared. Lower concentrations were obtained 

 from a "stock" solution by diluting with sterile distilled water in 

 sterile test tubes using graduated pipettes which had previously been 

 plugged at the upper end and then sterilized. 



The necessary alcohol solutions were prepared from "absolute" 

 alcohol (99-5 %). Formaldehyde solutions were obtained by taking 

 one part of Schering's Formalin (40 %) and adding 39 parts distilled 

 water, thus producing a 1 % "stock" solution. The chloroform was 

 added directly by means of a pipette. Thymol was weighed out and 

 added directly, after increasing the 9 c.c. bouillon to 10 c.c. by the 

 addition of 1 c.c. sterile water. Benzoic acid and salicylic acid were 



