280 
Extracts from British and Foreign Journals. 
POISON-PROOF ANIMALS. 
There are many cases on record of mites and insects 
having been found living on irritating vegetable substances. 
Cayenne pepper, ergot of rye, ginger, &c., are peculiarly liable 
to their attacks. But it has been considered that in these 
cases the starchy and soft fibrous matter only has been eaten, 
the active principle being rejected. Recent observations, 
however, would seem to indicate that these animals not only 
partake of each constituent of the food, but will subsist on 
such actual undiluted alkaloids as strychnine and morphine. 
In the course of a microscopical examination of the saline 
efflorescences which often form on the surface of the ordinary 
vegetable extracts used in medicine, Mr. Attfield, Demon¬ 
strator of Chemistry at St. Bartholomew’s Hospital, met with 
several colonies of little animals. Entomologically, these 
minute beings were very interesting; for, on the authority of 
Mr. Busk, F.R.S., three of the groups examined were 
decided to be members of two new genera, and probably 
three distinct species, of acari. But other curious facts 
seemed to be indicated by the circumstances under which 
these mites were living. Some were thriving on extract of 
colocynth, others on taraxacum, and many on extract of nux 
vomica. Now, considering that all extracts have once been 
liquid, and are therefore perfectly homogeneous, the con¬ 
clusion is irresistible that an animal, however minute, must, 
in taking a mouthful of such food, be partaking of a portion 
of every constituent; and that an acarus, therefore, in eating 
nux vomica must be swallowing strychnine. But to prove 
incontestably that mites live and thrive upon food that is to 
man a deadly poison, Mr. Attfield secured some lively, 
growing specimens from the nux-vomica extract, and, after 
searching them under high magnifying power, in order to be 
certain that no extract was accidentally adherent to their 
bodies, confined them singly in glass microscope cells, some 
with strychnine to feed upon, others without food of any 
kind. In less than two days the foodless ones were all dead, 
killed doubtless by starvation ; while those supplied with 
strychnine were at the end of two months as lively as ever, 
and had, of course, increased in size. Another curious fact 
concerning these remarkable creatures is their utter indif- 
