A NEW APPARATUS FOR OBTAINING SIMULTANEOUS 



CULTURES OF ANY DESIRED AGE FOR 



COMPARATIVE STUDY 



R. G. PERKINS 

 From the Laboratories of Hygiene and Bacteriology, Western Reserve Medical School 



Received for publication June 2, 1917 



In the course of a series of investigations of the morphology 

 of B. diphtheriae, it became necessary to study cultures of dif- 

 ferent ages on account of the well recognized fact that the 

 morphology varies from hour to hour. It is of course simple 

 enough to get eighteen-hour cultures, twenty-four-hour cul- 

 tures and cultures five, six or seven hours old, but unless the 

 investigator is living at or near the laboratory, there are many 

 intervals which are very inconvenient. To avoid this difficulty, 

 and to avoid also the multiplicity of inoculations necessary for 

 any long series, an attempt was made to develop an apparatus 

 which would give one a complete series of cultures of different 

 ages with a single inoculation. This has been done successfully 

 in the following manner. 



Through the Waterbury Clock Company a small eight-day 

 movement was obtained which had been so arranged that the 

 hour hand revolved once in twenty-four hours instead of once 

 in twelve hours, as do the twenty-four-hour clocks much used 

 by foreign railroads. This was set horizontally and a table ar- 

 ranged to be carried by the twenty-four-hour wheel. The table 

 was so fitted that vertical swab holders could be fastened at vari- 

 ous points and would of course make a twenty-four-hour circle. 

 On a vertically adjustable hanger an open inverted plate contain- 

 ing a solid medium was suspended so that the surface of the agar 

 was parallel to and immediately above the swab-carrying table. 

 When the sterile swab was inoculated with a given culture and 

 by means of the adjustment brought into contact with the under 



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