Parasitic Worms.—­Of these entozoa, the Filaria medinensis, or Guinea-worm, which burrows in the cellular tissue under the skin, is well known in the north of the island, but rarely found in the damper districts of the south and west.  In Ceylon, as elsewhere, the natives attribute its occurrence to drinking the waters of particular wells; but this belief is inconsistent with the fact that its lodgment in the human body is almost always effected just above the ankle.  This shows that the minute parasites are transferred to the skin of the leg from the moist vegetation bordering the footpaths leading to wells.  At this period the creatures are very small, and the process of insinuation is painless and imperceptible.  It is only when they attain to considerable size, a foot or more in length, that the operation of extracting them is resorted to, when exercise may have given rise to inconvenience and inflammation.

These pests in all probability received their popular name of Guinea-worms, from the narrative of Bruno or Braun, a citizen and surgeon of Basle, who about the year 1611 made several voyages to that part of the African coast, and on his return published, amongst other things, an account of the local diseases.[1] But Linschoten, the Dutch navigator, had previously observed the same worms at Ormus in 1584, and they are thus described, together with the method of removing them, in the English version of his voyage.

[Footnote 1:  In DE BRY’S, Collect, vol. i. p. 49.]

“There is in Ormus a sickenesse or common plague of wormes, which growe in their legges, it is thought that they proceede of the water that they drink.  These wormes are like, unto lute strings, and about two or three fadomes longe, which they must plucke out and winde them aboute a straw or a feather, everie day some part thereof, so longe as they feele them creepe; and when they hold still, letting it rest in that sort till the next daye, they bind it fast and annoynt the hole, and the swelling from whence it commeth foorth, with fresh butter, and so in ten or twelve dayes, they winde them out without any let, in the meanetime they must sit still with their legges, for if it should breake, they should not, without great paine get it out of their legge, as I have seen some men doe.” [1]

[Footnote 1:  JOHN HUIGHEN VAN LINSCHOTEN his Discours of Voyages into the Easte and West Indies. London, 1599, p, 16.]

The worm is of a whitish colour, sometimes inclining to brown.  Its thickness is from a half to two-thirds of a line, and its length has sometimes reached to ten or twelve feet.  Small specimens have been found beneath the tunica conjunctiva of the eye; and one species of the same genus of Nematoidea infests the cavity of the eye itself.[1]

[Footnote 1:  OWEN’S Lectures on the Invertebrata, p. 96.]

Planaria.—­In the journal already mentioned, Dr. Kelaart has given descriptions of fifteen species of planaria, and four of a new genus, instituted by him for the reception of those differing from the normal kinds by some peculiarities which they exhibit in common.  At Point Pedro, Mr. Edgar Layard met with one on the bark of trees, after heavy rain, which would appear to belong to the subgenus geoplana.[1]