MINERALS IN NUTRITION 37 



group, varied greatly from day to day, so that graphs made of the several 

 series of counts presented a confusing array of "hills and valleys" that had 

 no apparent meaning. The data were then considered as averages : for 

 example, the B. coli counts for the rats in each "milk" group were averaged 

 for each dietary period. In experiment 1, the averages for the preliminary 

 hamburg-steak diet were taken as 1, and the averages for the meat-plus- 

 milk and for the all-milk diet periods were expressed as ratios of 1. 

 In experiment 2, the averages for the Purina fox chow feeding period 

 were taken as 1, and the averages for the chow-plus-milk and for the all- 

 milk diet periods were expressed as ratios of 1. Again, there was no 

 evidence that iodine exercised any influence on the results. If a trend 

 was noticed in one group of rats, the results of another similarly treated 

 group would show a trend in a different direction. 



If there had been positive evidence of any influence on the part of the 

 iodine, a tabulation and analysis of results would be presented here. Since 

 there are no positive findings to report, a detailed presentation of data 

 seems useless. The value of averaging the data is questionable because, 

 if a treatment for an illness is to be effective, a daily progressive improve- 

 ment in condition is desired rather than extreme well-being one day and 

 a serious relapse the next. In the fecal-flora findings of these two experi- 

 ments, the results were up and down and no progressive tendency was 

 noted. 



Kelp Feeding 



Since the iodine added to the ration in the first two experiments was in 

 inorganic form, it was decided to investigate the effect of organically 

 combined iodine on the fecal flora of rats. Kelp has been used as a source 

 of iodine in animal feeding experiments (1, 3, 7), so it was chosen for 

 this study. Kelp supplies other minerals as well, but it is an especially 

 good source of iodine. 



Eight young rats were fed Purina fox chow for a preliminary period 

 of four weeks. Then 10 percent by weight of kelp was added to the ration 

 and the experiment was continued for eight weeks more. Bacteriological 

 examinations were made twice each week. Since the gas and hydrogen- 

 sulfide production, and the aerobic and anaerobic counts, had not yielded 

 any significant results in the first two experiments, the examinations for 

 this experiment were limited to the aciduric and coliform counts. 



Again, as for the first two experiments, results from individual rats 

 from day to day, or from any group for any one examination period, were 

 so erratic that the only practical method of presenting the data was to 

 average the counts of the whole group of rats for the whole of each diet 

 period. The data were not sufficiently significant to justify the presenta- 

 tion of a table. The results can be summarized in the statement that there 

 was no material change in the aciduric counts; and after the kelp was 

 added to the diet, the coliform counts became almost four times as great 

 as those obtained when the chow alone was fed. The addition of kelp 

 to the diet did not cause any inhibition of bacterial growth, and there 

 was a substantial stimulus of the growth of coliform bacteria. Further 

 study would be necessary to determine what component of the kelp was 

 responsible for this result. 



