184 



Profs. Percy Frankland and Marshall Ward. 



from (D), the cotton-wool plug is extracted from (E), the latter 

 tube is carefully heated with a Bunsen flame to destroy any organ- 

 isms that may be resting on its open extremity, and by inclining (D) 

 the water can be made to flow out into the sterilised vessels placed 

 for its reception without undergoing any contamination. 



Infection of the Water with Anthrax. — In this first series the an- 

 thrax bacilli were taken from an agar- agar cultivation of about 

 three weeks age, in which it was known by previous microscopic 

 examination that spores were abundantly present. 



The surface of the agar-agar was scraped with a sterile platinum 

 loop, care being taken to remove the growth with as little as 

 possible of the culture material. Five loops full in all were' taken 

 and transferred to a small sterile stoppered bottle containing about 

 50 c.c. of Thames water which had been steam- sterilised. The 

 contents were then violently agitated for some fifteen minutes in 

 order to break up the conglomerations of bacilli and spores, and 

 effect as uniform a distribution as possible. This may be termed the 

 "first attenuation." 



From this first attenuation four portions of 2 c.c. each were re- 

 moved with sterile pipettes and introduced respectively into four large 

 flasks, each containing about 2 litres of the waters for experiment, 

 viz. : — 



(a.) Thames water, in natural state. 

 (b.) Ditto after filtration through Swedish paper, 

 (c.) Ditto after filtration through porcelain. 

 (#.) Ditto, after sterilisation by steam. 



The waters thus infected were well shaken in the large flasks con- 

 taining them so as to ensure complete mixture, and the contents of 

 each flask was then distributed in a number of small sterilised 

 conical flasks plugged with sterile cotton wool. In the case of each 

 of these infected waters some of the small conical flasks were placed 

 in an incubator maintained at 18 — 20° C, the summer temperature of 

 surface waters, whilst others were put into a refrigerator in which a 

 temperature of 6 — 10° C. was preserved. 



The distribution and arrangement will be readily apparent from 

 the following tabular statement : — 



Thames Water in Natural State. 



Un- f 2 flasks in incubator. Infected I 4 flasks in incubator. 

 infected\ „ refrigerator. \S „ refrigerator. 



Thames Water after Filtration through Swedish Paper. 



Un- f 2 flasks in incubator. I j rL f ecte( j f 5 flasks in incubator, 

 infected \ „ refrigerator. ( I » refrigerator. 



