PUTEEFACTION AND INFECTION. 63 



The tiniest drop had remained in it by capillary attrac- 

 tion from the preceding day. This was blown on to a 

 slide, covered, and placed under the microscope. An 

 astonishing exhibition of life was my reward. Thus on 

 the scent, I looked through my pipettes, and found two 

 more with the smallest residual drops at the ends : both 

 of them yielded a field rampant with life. The Bacteria 

 darted in straight lines to and fro, bending right and 

 left along the line of motion, wriggling, rotating longi- 

 tudinally, and spinning round a vertical transverse 

 axis. Monads also galloped and quivered through the 

 field. From one of these tiny specks of liquid was 

 obtained an exhibition of life not to be distinguished 

 from that which had astonished me on the 21st. 



Obviously the phenomenon then observed was due 

 to the employment of an unclean pipette. Equally 

 obvious is it that in inquiries of this nature the experi- 

 menter is beset with danger, the grossest errors being 

 possible when there is the least lack of care. 



The chamber here operated on had been opened 

 with a view to testing the capacity of the infusions 

 within it to develop and maintain life. For four weeks 

 they had remained perfectly dear. Two days after 

 the door was opened and the common laboratory air 

 admitted all six tubes were turbid, and swarming with 

 Bacteria. Some of them were very long, and their wrig- 

 gling and darting hither and thither very impressive. 



The same chamber was again thoroughly cleaned, 

 sealed, and permitted to remain quiet until the floating 

 matter had subsided. On the 17th of November a 

 fresh infusion of turnip was introduced into it through 

 the pipette, boiled in an oil-bath, and again abandoned 

 to the air of the case. 



After several months the infusion in every tube of 

 the six remained as clear as it was on the day of its 

 introduction. 



