226 
BACTERIOLOGY: JACOBS AND HEIDELBERGER 
6. The interpretation of the growth of these plants by Mendelian fac- 
tors is further strongly supported by the distribution of the standard 
deviations of the plants with different relative sizes. Thus it has been 
shown that the extreme plants which would be more nearly homozygous 
and for this reason less variable are, as a matter of fact, some 50 per 
cent less variable than the plants in the middle class after all allowance 
has been made for the difference in the size of the means. 
This is a preliminary abstract of a paper with the same title now in 
press in the Zeitschrift fiir induktive Abstammungs- und Vererbungslehre. 
ON A NEW GROUP OF BACTERICIDAL SUBSTANCES 
OBTAINED FROM HEXAMETHYLENETETRAMINE 
By Walter A. Jacobs and Michael Heidelberger 
ROCKEFELLER INSTITUTE FOR MEDICAL RESEARCH, NEW YORK 
Presented to the Academy. February 17, 1915 
Ever since the introduction of hexamethylenetetramine into medicine, 
this drug has attracted wide attention owing to its far-reaching possi- 
bihties as an internal antiseptic. In addition to its rapid appearance in 
the urine it is found after ingestion in practically all the body secretions, 
including even the cerebrospinal fluid. It is fairly well established that 
the antiseptic action of the drug is due to the liberation from it of for- 
maldehyde by virtue of the acidity of the medium in which it acts, but 
that its diffusion throughout the body is a physical property of the un- 
decomposed molecule. In other words, hexamethylenetetramine is but 
a vehicle for formaldehyde, and if the two conditions are satisfied, firstly, 
its appearance in large enough amount in the locality desired, and sec- 
ondly, its cleavage to formaldehyde, a local internal antiseptic action 
might be expected. Owing, among other things, to the alkalinity of 
most of the body fluids the limitations set by these prerequisites are 
obvious. 
Numerous attempts have already been made to achieve by proper 
chemical variation an improvement in the action of the drug. Such 
attempts, however, which have been confined almost entirely to com- 
binations of hexamethylenetetramine with acids and phenolic compounds, 
have offered few advantages over the original drug. It seemed to us 
that more promising results might be obtained by a more direct varia- 
tion of the hexamethylenetetramine molecule itself and a brief outline 
of the facts observed in the course of this work is the subject of the 
following: 
The molecule of hexamethylenetetramine functions as a tertiary base, 
