nV R. GREIG-SMITH. 



71 



The eNpfi'iment showed a distinet advance of I'roiH +0° to -(-9° in the acidity 

 with the sugai-s iind a reduction of about the same number of degrees with glycerin 

 during' the four days' growth at 28°. 



A more comprehensive test was iiiaik' into the effect of various sources of 

 carbon upon the jiroduction of ropiness. A medium containing 2 % of sugars, etc., 

 0.25% meat extract and 0.5% of crystalline sodium phosphate was prepared 

 and portions were seeded with the phases. 



Table xiii. — Sources of Carbon (1). 



When the experiment was well undi-r way, it was found tnat ])hase A2 and 

 (A2a) had altered and contained more oi- less of Al, a fact that should be taken 

 into account in considering the disapi)earauce of the ropiness. It had also been 

 discovered that the growth of phase Al in glycerin caused some of the bacteria 

 to assume the phase A2, possibly on account of the medium beeoming alkaline in 

 contrast to the acidiiication in the presence of sugars. The results of this ex- 

 l)eriment engender the belief that glycerin is the only substance of those tested 

 wliich can alter Al into A2 and that dextrose can rapidly alter A2 into Al. The 

 role these sulistances play is presumably in the suppre.ssion or exaltation of the 

 ]>ower of the bacteria to secrete a slime dissolving enzyme. 



Meanwhile it had been determined that the saline constituents of the medium 

 had an influence in the production of the ropiness, especially with i)hase H2. la 

 a saline test, Table xvi., Al gave a ropy medium in the pi-esence of sodium 

 chloride and with no other salt, while pota-ssium citrate was most favotirable wirli 

 phase B2 and as good as several others with phase A2 (A2a). A nieilium was 

 accordingly prepared containing 2 '^c of carboliydrate or other nutrient, 0.25 % 

 meat extract and 0.2 % of common salt for phase Al and of potassium citrate for 

 the others. The bacteria had been pickeil from plates three days previously. 



