14 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



of 22° to 27°C. The percentages used in this paper are percentages 

 of saturation at these temperatures, i.e., the volume of saturated 

 borate solution per hundred of the final enz3rme buffer solution. The 

 saturated borate solutions ranged from pH 9.1 to 9.3. In 200 ml. of 

 enzjnxie buffer solution the addition of about one-half gram of enzyme 

 powder resulted in slight but obvious drops in pH, in solutions below 

 25 percent saturated, or 0.8 gram borax per hundred. Solutions in 

 the range from 5 to 20 percent saturated often became disagreeably 

 contaminated wdth bacteria in 10 days. Sometimes, but very infre- 

 quently, solutions from 25 to 33 percent saturated developed dis- 

 agreeable odors in this period, perhaps owing to either excessive initial 

 bacterial contamination from unclean containers or to a failure to 

 obtain complete saturation of the initial borate solution. Generally, 

 solutions from 30 percent saturated upward are expected to prevent 

 excessive bacterial growth over a period of time sufficient to obtain 

 the maximum digestive use of an enzyme. 



The rate of pH drop depends on the relative volume of the solution, 

 the quantity of buffer in solution, and the digestive activity. Active 

 5 percent saturated borate solutions frequently dropped from pH 8.8 

 or 8.9 to pH 6.7 or lower in 10 days without adequately clearing 

 specimens. Similar 20 percent solutions dropped from pH 9.1 or 

 9.2 to pH 8.2-8.5, and 50 percent solutions dropped from pH 9.2 to 

 pH 8.9-9.0 in the same time, but both with virtual clearing of speci- 

 mens. Solutions containing 15 percent or less saturated borate or 60 

 percent or more took longer consistently to clear specimens than did 

 solutions between these ranges. Saturated solutions of borate required 

 the longest activity. Little difference in clearing rate was noted in 

 20 to 50 percent saturated solutions, wdth the best results believed 

 to have been in those 25 to 33 percent saturated. Numerous tests of 

 the 30 percent solution indicate that it remains desirably stable and 

 infrequently drops below pH 8.0, even after several weeks. 



Solutions of 2 to 6 grams borate per thousand, corresponding 

 approximately to solutions 20 percent saturated or less, gave similar 

 rapid drops in pH and quickly developed extensive bacterial cultures 

 without adequate specimen clearing. Those with 8 to 16 grams borate 

 per thousand gave results similar to the 25 to 50 percent saturated 

 solutions. Borate solutions of 18 to 22 grams per thousand, corres- 

 ponding to about 55 to 70 percent saturated, permitted slow clearing, 

 similar to solutions with 6 grams or less. Borax-enzyme solutions of 

 volumes 10 to 40 times that of the specimens have generally been 

 found adequate. Excess volume of solution, several hundred times 

 that of the specimen, resulted in a dilution of enzyme, and it nearly 

 doubled the specimen clearing time. On the other hand, an inadequate 

 volume of solution quickly becomes saturated with digestion products, 



