656 
EDITORIAL OBSERVATIONS. 
adduced. Is it not strange that a vermicule which attaches 
itself to a mouse should only arrive at maturity by trans¬ 
ference to the tissues of a cat ? It is also known that the 
echinococcus in pork, when eaten by dogs, gives rise to the 
tapeworm in that animal, and that segments of the last-named 
parasite will produce hydatids in the brain. In like manner 
the ovum of the fluke —Distoma hepaticum —does not find 
its way directly into the ducts of the liver of the sheep, hut 
undergoes a change into the form of chrysalis or larva in the 
body of a fresh-water snail, or some small aquatic animalcule, 
the circular germ it sends forth being ciliated and capable 
of attaching itself to the bodies of these animals, and then 
penetrating them. 
These observations have been evoked by the perusal of an 
interesting series of experiments instituted by M. Pasteur, 
and published by him in the Comptes Rendus , a translation of 
which appears in the American Journal of Science, by Dr. 
"White. In his introductory remarks he says: 
“The theory of spontaneous generation was long since 
proposed to account for the origin of beings whose germs 
were too minute or too obscure to attract attention. One 
after another the different organisms supposed to arise 
from spontaneous generation have been proved to originate 
from germs. At present the question of spontaneous genera¬ 
tion concerns only the origin of entozoa and those minute or¬ 
ganisms which can be studied only with the aid of the micro¬ 
scope,as moulds (minute fungi) and infusoria, both animal and 
vegetable. The common theory that the spores or germs of 
these minute organisms are constantly floating in the atmos¬ 
phere, ready to start into activity whenever they meet with a 
suitable nidus has found an able advocate in M. Pasteur. 
“ In order to collect and examine the solid particles floating 
in the atmosphere, Pasteur placed soluble gun-cotton in a 
glass tube, and, by means of an aspirator, caused a current of 
atmospheric air to pass through it for several hours. The 
cotton was then dissolved in a mixture of alcohol and ether, 
and the atmospheric dust, deposited at the bottom of the 
fluid in a conical glass, was examined in the microscope. 
The sediment thus collected contained grains of starch and 
such other dust as is ordinarily found on surfaces exposed to 
the air. When submitted to the action of concentrated 
sulphuric acid, the starch was soon dissolved, while other 
