168 
PACIFIC SCIENCE, Vol. IV, July, 1950 
METHODS 
The method of measuring the antibacterial 
properties of plants is essentially the same as 
that devised by the Oxford group (Abraham 
et al., 1941 ) for assaying penicillin and since 
adapted to the assay of other antibiotics pro- 
duced by micro-organisms. It is a method 
which has been used in other parts of the 
world to appraise medicinal plants (Pederson 
and Fisher, 1944; Lucas and Lewis, 1944; 
Sanders, Weatherwax, and McClung, 1945; 
Carlson et al., 19 46; and many others). It 
is based upon the assumption that an agent 
which acts upon a test organism to achieve 
a particular effect will also act upon other 
related organisms in a similar manner. While 
the assumption is not always substantiated by 
experimental evidence, it is tenable often 
enough to give the method some usefulness 
as a "screening test" for distinguishing agents 
that are "likely” to be effective from those 
which are "likely” to be ineffective. It is a 
method which has its deficiencies, certainly, 
but it is better than no method at all. 
The plants to be studied were collected 
over a period of 2 years as they could be 
found on the island of Oahu. Most of them 
were obtained on or near the University of 
Hawaii campus and in the adjacent Manoa 
Valley. Whenever feasible, specimens of the 
complete plant — roots, stems, leaves, buds, 
flowers, and fruits — were obtained, either all 
at once or during those seasons when they 
could be found. In the case of a plant of 
which only certain portions had been used 
in the native pharmacopeia, we were careful 
to collect and to study at least those pre- 
scribed portions of the plant if not all of it. 
Many of the plants, or many of the parts of 
the different species, were tested several times 
during the course of our study, in several in- 
stances by each of us independently. 
The specimens were taken to the labora- 
tory soon after they were collected, and either 
were subjected immediately to the process of 
assay or were frozen and held at — 10° C. 
until they could be studied. 
Extracts of the whole plants or of certain 
separated portions of them — as, for example, 
the roots, the stems, the leaves, the flowers, 
the fruits, or of any indicated combinations 
of these — were obtained by first cutting the 
plant material into small pieces and by then 
subjecting these fragments to high pressures, 
ranging from 15,000 to 20,000 pounds per 
square inch, achieved by means of a Carver 
hydraulic press. No water or solvent of any 
kind was added to the plant material, and in 
almost all cases the specimens yielded ample 
amounts of tissue fluids for the purposes of 
the study. 
The extracts of the different portions of 
the plants were kept in separate beakers, and 
were placed immediately in a refrigerator 
until the next step in the assay could be per- 
formed. In most instances the period of stor- 
age was only 1 to 2 hours; in no case was it 
longer than 4 hours. 
Most of the extracts were assayed for their 
antibacterial effect upon three test strains of 
bacteria: Micrococcus pyogenes var. aureus 
(until recently known as Staphylococcus 
aureus ), Escherichia coli, and Pseudomonas 
aeruginosa. A few of those extracts studied 
early in these investigations were tested 
against M. pyogenes var. aureus and E. coli 
only. Seventeen of the plants, which the lit- 
erature described as having been employed 
to combat intestinal infections, were tested 
against five different strains of enteric patho- 
gens as well as against the three standard 
cultures. The enteric pathogens used were: 
Salmonella typhosa, Sal. montevideo, Sal. 
schottmuelleri, Shigella paradysenteriae BH, 
and Shig. paradysenteriae III-Z. Cultures of 
all of these test organisms were obtained from 
the stock culture collection of the Depart- 
ment of Bacteriology, University of Hawaii. 
Pure cultures of the test bacteria were 
grown in nutrient broth at 37° C. for 24 
hours before they were used. When an assay 
