518 GEORGE E. HOLM AND JAMES M. SHERMAN 



are exceptions and which, in concentrations thus far tried, have 

 proved highly retarding in their action. These ions are the 

 sulphocyanate and fluoride. Whether in lower concentrations 

 they might not prove but slightly retarding or even beneficial 

 to growth remains to be ascertained. The position of the SO4 

 radical with regard to effect upon bacterial growth is also some- 

 what at variance with its usual position in the lyotropic series. 

 Instead of being found opposite the iodine end of the series it 

 is found next to the CI and I radicals. 



While these are deviations from the usual order, it is not 

 surprising since in many of the phenomena in biochemistry the 

 lyotropic order does not strictly compare with the usual order 

 as determined by effects upon surface tension, viscosity, etc., 

 especially at different concentrations and temperatures. We 

 must also remember that here we are dealing with an added 

 factor which is not present with proteins in solution or with 

 colloids in general; that is, the life of an organism. Since this 

 is our measure of effects it must be taken into account. We 

 do not know what properties affect viability most, and conse- 

 quently we have no means of knowing what mechanism causes 

 retarding and inhibitory effects. There seems to be, as might 

 be expected, an order of specificity which must be taken into 

 account. 



The general order of the lyotropic series, however, holds at 

 pH 7.0 CI and I are found at one end of the series aiding or 

 accelerating action, while the citrate, acetate, and oxalate at 

 the other end retard growth. 



Considering the effect of cations, we have a close analogy 

 between action here and action of salts in the animal body. 

 As might be expected, there is little difference between the Na, 

 K, and NH4 ions. With Mg the action begins to manifest 

 itself, although it is greatly modified by the anion effect. The 

 calcium ion produces its characteristic strong effect. 



It is in media of different H-ion concentrations that these 

 effects become significant. In the region of optimum growth the 

 influences are not exceedingly marked, but as we near the H-ion 

 concentrations which mark the limits for growth of Bad. coli 



