558 BIOLOGY OF PNEUMOCOCCUS 



icity of phenol, cresols, and glycerol by physiological tests on 

 mice. It was impossible to establish a definite minimal lethal dose 

 of the substances because of marked variations in susceptibility of 

 the test animals. It was found, however, that tricresol and phenol 

 exerted approximately the same germicidal effect. Voegtlein 

 (1918) 14S1 studied the effect of the addition of tricresol and phenol 

 to antipneumococcic serum introduced intravenously into mon- 

 keys, cats, and dogs. The doses given were calculated to corre- 

 spond to the amounts given in the treatment of pneumonia. Voegt- 

 lein concluded that the addition of tricresol or phenol to antipneu- 

 mococcic serum in concentrations not exceeding 0.5 per cent does 

 not seem to impart to the serum toxic properties which might give 

 rise to serious symptoms following its intravenous administration. 

 It was suggested, however, that serum containing phenol should 

 not be given to patients with nephritic complications because of 

 the injurious action of phenol on the kidney. 



A mercurial preparation, Merthiolate, has been recommended 

 as a preservative for biological products. Jamieson and Powell 

 (1931 ) 677 reported that the substance is highly effective as a 

 germicide, possesses low toxicity, and is not subject to precipita- 

 tion in protein solutions. The agent has not, however, come into 

 general use as a preservative in antipneumococcic serum. 



Malcolm (1931) 857 studied the germicidal and toxic effects of 

 various chemical substances, and found that the mercury com- 

 pounds, Metaphen and Mercurophen, possessed higher bactericidal 

 powers than phenol and tricresol, and were relatively less toxic, 

 thus permitting a wider margin of safety when used as preserva- 

 tives for biological products. Another advantage possessed by the 

 two mercury compounds is that at their effective germicidal 

 strength they do not precipitate proteins. Of the preservatives 

 studied, Malcolm concluded that Mercurophen was the most satis- 

 factory, with Metaphen second in order of effectiveness, and that 

 both were superior to phenol or tricresol. At the present time both 

 phenol and tricresol in final concentrations not exceeding 0.5 per 



