BACTERIA AND THEIR ALLIES 173 



and beet-root, while alcohol and carbonic acid were produced in 

 the same way as with the fruits, and the alcoholic ferment was 

 absent as before. Bacteria of different sizes were invariably found 

 in the acid fluid which impregnated the softened tissues of the 

 vegetables in question. No details on this point were given, and 

 the authors do not appear to have made any further observations 

 on the subject ; nor did Pasteur offer any reply to such statements, 

 though he had previously been working at the same subject 

 himself.' 



Having determined to endeavour to obtain some more definite 

 information as to the appearance of Bacteria in this way, I have, 

 during the last two or three years, made various experiments, in 

 which small Potatoes, after being carefully washed, were allowed 

 to soak for a time in different germicidal fluids. First of all, 

 I employed a solution of mercury bichloride (i : 2000) ; while 

 later, after the preliminary washing, the potato was allowed to 

 soak in a five per cent. formaUn solution. The screw-top bottle 

 in which the potato was placed was also thoroughly washed out 

 with one or other of these fluids. In these cases organisms were 

 found within, but also, after a time, on the surface of the potatoes 

 thus treated ; so that these particular experiments and methods 

 were rejected as not yielding trustworthy results. This was 

 necessary because, at a rather earlier date, Pasteur had stated that, 

 in experiments which he had made with fruits no ferment 

 organisms ever appeared. He declared again that the tissues of 

 healthy fruits and vegetables were germless, but intimated that, 

 unless care was taken, they might make their way in from without.'' 



Subsequently, I used a stronger solution of formalin, and have 

 never since found organisms on or near the surface, though they 

 have often been found within cells in the central portions of the 

 potato. I will now, therefore, give brief details of some of the 

 most successful of these experiments. 



In July, 1901, a small new potato, after being well washed, was 

 allowed to soak in a ten per cent, solution of formalin for ten 

 minutes, in a small screw-top bottle, and during this time the fluid 

 was frequently shaken so as to cover the whole inner surface of 

 the bottle. At the expiration of the time named, the top was 

 unscrewed, the fluid poured out, and the top then tightly refixed, 

 leaving the potato itself and the inner surface of the bottle wet 



' " Compt. Rend.," 1872, ii., p. 788. 

 = Loc. cit., 1872, ii., pp. 788 and 981-2, 



