INTRODUCTION. | 19 
claims that these are not parasites, but mutualists, and are rather 
of advantage than otherwise to the host, since they clean up the cast- 
off matter. I must differ, however, from the learned author in this 
opinion, since the presence of these lice and the irritation of their 
movements is plainly evidenced by the animals in their sometimes 
frantic efforts to rid themselves of the pests. 
The scratching of horses and cattle against posts, rails, ete., the 
dusting of chickens in ashes or road dust, and, finally, the effects to be 
observed in the weakening of calves, colts, etc., infested by these pests 
settles the question of their damaging effects, to my mind, decidedly in 
the affirmative. 
As carriers of contagious or infectious diseases, the insects which 
attack domestic animals present an important subject for study, 
especially so since the increase of our knowledge regarding such dis- 
eases and their origin in the multiplication of micro-organisms. As 
yet comparatively little is known upon this point, but enough to show 
that it is deserving of greater attention than it has as yet received. | 
It has been shown that elephantiasis is due to germs carried by mos- 
quitoes and it seems not improbable that other diseases may be carried 
by this same universal pest. The mosquito partially filled with the 
blood of one animal suffering from some infectious disease, alighting 
upon the body of another and inserting its already wet beak, may 
transfer with it germs of the disease as well as its own subtle poison, 
more likely still if it be crushed and the blood with which it is filled is 
spread over the pierced tissue. Since the above was written the fol- 
lowing item in Psyche, Vol. V, page 24, has appeared and is so much 
to the point that we insert it here: 
Insects as authors of epidemics.—Dr. R. L. Maddox, in a paper read before the Royal 
Microscopical Society, details the results of further experiments in feeding insects, 
especially the common blow-ily, on the comma bacillus. His observations include a 
large number of microscopical determinations. The results of all his investigations 
lead him to believe that the comma bacillus from cultures can pass in a living state 
through the digestive tubes of some insects, and, through this fact, that such insects 
are likely to become an important means of distributing disease, especially to ani- 
mals that feed upon them. This is in accordance with the views of Dr. Grossi, that 
“insects, especially flies, may be considered as veritable authors of epidemics and 
agents in infectious maladies.” (Scientific American, December 18, 1886.) 
Surgeon-General Sir William Moore (Medical Magazine, July, 1893) 
regards the dissemination of disease by flies as a matter looked upon 
with too much indifference, and instances an epidemic of anthrax 
which was spread by flies which had covered a carcass of a dog 
thrown into a ditch in Cortal. He quotes the experiments of Lawt- 
schenks with flies and cholera germs, and observes that it is worth 
noticing, in that in India it is during the time and season of the 
greatest prevalence of cholera that flies most abound. The possi- 
bility of flies carrying the organisms of typhoid fever and phthisis is 
suggested, and the belief is expressed that leprosy is often conveyed 
by flies, which appear to be particularly fond of leprous sores, and the 
