Oil is the only means of loosening the hold of a tick; this suffocates him and he dies; but he leaves an amount of inflammation in the wound which is perfectly surprising in so minute an insect. The bite of the smallest species is far more severe than that of the large buffalo or the deer tick, both of which are varieties.

Although the leeches in Ceylon are excessively annoying, and numerous among the dead leaves of the jungle and the high grass, they are easily guarded against by means of leech-gaiters: these are wide stockings, made of drill or some other light and close material, which are drawn over the foot and trowsers up to the knee, under which they are securely tied. There are three varieties of the leech: the small jungle leech, the common leech and the stone leech. The latter will frequently creep up the nostrils of a dog while he is drinking in a stream, and, unlike the other species, it does not drop off when satiated, but continues to live in the dog's nostril. I have known a leech of this kind to have lived more than two months in the nose of one of my hounds; he was so high up that I could only see his tail occasionally when lie relaxed to his full length, and injections of salt and water had no effect on him. Thus I could not relieve the dog till one day when the leech descended, and I observed the tail working in and out of the nostril; I then extracted him in the usual way with the finger and thumb and the tail of the coat.

I should be trespassing too much upon the province of the naturalist, and attempting more than I could accomplish, were I to enter into the details of the entomology of Ceylon; I have simply mentioned a few of those insects most common to the every-day observer, and I leave the description of the endless varieties of classes to those who make entomology a study.

It may no doubt appear very enticing to the lovers of such things, to hear of the gorgeous colors and prodigious size of butterflies, moths and beetles; the varieties of reptiles, the flying foxes, the gigantic crocodiles; the countless species of waterfowl, et hoc genus omne; but one very serious fact is apt to escape the observation of the general reader, that wherever insect and reptile life is most abundant, so sure is that locality full of malaria and disease.

Ceylon does not descend to second-class diseases: there is no such thing as influenza; whooping-cough, measles, scarlatina, etc., are rarely, if ever, heard of; we ring the changes upon four first-class ailments—four scourges, which alternately ascend to the throne of pestilence and annually reduce the circle of our friends—cholera, dysentery, small-pox and fever. This year (1854) there has been some dispute as to the routine of succession; they have accordingly all raged at one time.

The cause of infection in disease has long been a subject of controversy among medical men, but there can be little doubt that, whatever is the origin of the disease, the same is the element of infection. The question is, therefore, reduced to the prime cause of the disease itself.

A theory that animalcules are the cause of the various contagious and infectious disorders has created much discussion; and although this opinion is not generally entertained by the faculty, the idea is so feasible, and so many rational arguments can be brought forward in its support, that I cannot help touching upon a topic so generally interesting.

In the first place, nearly all infectious diseases predominate in localities which are hot, damp, swampy, abounding in stagnant pools and excluded from a free circulation of air. In a tropical country, a residence in such a situation would be certain death to a human being, but the same locality will be found to swarm with insects and reptiles of all classes.

Thus, what is inimical to human life is propitious to the insect tribe. This is the first step in favor of the argument. Therefore, whatever shall tend to increase the insect life must in an inverse ratio war with human existence.

When we examine a drop of impure water, and discover by the microscope the thousands of living beings which not only are invisible to the naked eye, but some of whom are barely discoverable even by the strongest magnifying power, it certainly leads to the inference, that if one drop of impure fluid contains countless atoms endowed with vitality, the same amount of impure air may be equally tenanted with its myriads of invisible inhabitants.