RED-SQUILL POWDERS AS RATICIDES 
5 
Kobert {17) quotes Kunkel's findings that red squill is more potent 
than white, that the outer scales act more intensely than the inner 
scales, and that the bulbs gathered in summer are more potent than 
those collected in the spring. 
Lantz {19), LerebouUet {20), George {12), Howarth (7^), and 
Schlupp {23) report the suitability of red squill as a rat poison under 
various conditions. Howarth states further that ''it is, moreover, 
regarded as comparatively harmless to domestic animals." W. K. 
Tonkin, rat officer of Middlesex County, England, reports ^ that 
phosphorus pastes, barium carbonate, and one or two proprietary poisons have 
on occasion been used, but freshly extracted squill, both as a lethal rat poison 
and by reason of its being comparatively harmless to domestic animals, has 
been found of greater use than any other poison. 
Boulenger {S) found that squill solution was the most effective rat 
poison, being three times as toxic as barium carbonate to rodents and 
also less harmful to domestic animals. 
Finally, the British Ministry of Agriculture and Fisheries {13) 
recommended the use of squill: 
Baits containing barium carbonate or red squill * * * recommended 
by the ministry, and if used as directed, and with proper precautions, are less 
dangerous than baits containing such poisons as arsenic, strychnine, and phos- 
phorus * * i^ecj squill is the safer, and it is advisable to use it in pref- 
erence to other toxic agents for application on farms and in places where special 
care is necessary owing to the presence of poultry, livestock, domestic animals, 
or stored food supplies * * *^ Owing to the peculiar chemical nature of red 
squill in its various forms, as sold for the destruction of rats and mice, users of 
these preparations should satisfy themselves that they obtain guaranteed toxic 
red-squill raticides. 
Recapitulating, the Hterature indicates that red squill is toxic to 
rats whether fed as the fresh bulb or as a powder, that it is essen- 
tially nontoxic to animals other than rats, and that white squill is 
nontoxic to rats {25). Apparently, the toxic principle has not been 
consistently isolated by chemical methods. 
EXPERIMENTAL PROCEDURE 
PREPARATION OF POWDER 
In the preliminary experiments, 24 powders were prepared from 
samples taken from a 900-pound keg of squill bulbs imported from 
Cagliari, Sardinia, in the fall of 1923 and kept in storage at 4° to 5° C. 
This entire series of powders was prepared by Otis F. Black and 
James W. Kelley, of the Office of Drug, Poisonous, and Oil Plants, 
Bureau of Plant Industry, United States Department of Agriculture. 
The outer, dry, reddish-brown husks, w^hich were found to be less 
toxic than the inner scales, were stripped from all bulbs. The bulbs 
were sliced and, in most instances, air-dried for several hours and 
placed in long glass tubes. A current of air was passed over the 
surface. The temperature was increased over a period of several 
days from room temperature to a given maximum, which was main- 
tained until constancy in weight indicated that the products were 
thoroughly dried. They were then removed and ground in a drug 
mill until the powder passed through a 40-mesh sieve. These powders 
contained 1 to 2 per cent of moisture. After being ground, all powders 
were placed in tightly closed screw-top vials. Details of time and 
temperature are given in Table 2. 
Personal communication. 
