A pH gradient agar plate 

 -  Nature,  178(4527), p.269-270, 1956 .
<br/><br/> IT is often advantageous for the microbiologist to know the pH limits within which a micro-organism will gl'OW, and the inftuence of pH on the antimicrobial action of various drugs. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>AGAR PLATE