Larvæ:.—Although the history of the development of the young
worms has not actually been ascertained, it is tolerably certain that the structural characters they exhibit, and the changes they undergo, are similar to those of other closely allied species. Thus, without doubt, the tree embryos are rhabditiform, and pass their larval lifetime in water, mud, and moist earth, After having undergone one or more changes of skin, attended with growth, they are possibly transferral to the human stomach.
Intermediate host—It is not certain that any intermediary bearer is necessary.
Remarks.— Water drinkers in tropical climates readily become the victims of this parasite, either by swallowing the free swimming larvae, or water insects containing the larvæ in a state of rest. The Dochmius duodenalis was discovered by Dubini, at Milan, in 1838, and its clinical importance in relation to the so-called Egyptian chlorosis was first announced by Griesinger. We now know that this destructive little parasite is a fertile cause of the wasting disorders of tropical countries generally: the affections termed tropical anæmia or hypoæmia being especially prevalent in the West Indies, in Cayenne, in Brazil, in Egypt, and in the Comoren Islands lying to the north-east of Madagascar. The worms are veritable bloodsuckers, behaving like leeches; probably, however, the loss of strength and diminution of vital power which they occasion is not so much due to the actual amount of blood abstracted as to the severe irritation resulting from the injuries they inflict upon the mucous membrane of the infested intestine.
Lit.—The Work of Leuckart; and especially a Memoir by Wucherer in Deutsches Archiv fur Klinische Meidicin}, Sept. 27, 1872, (s. 379—400.)
On the Microscopical Examination of Clay.
By The Rev. H. W. Crosskey, F.G.S.
A brief record of the results of considerable practical experience in the microscopical examination of clay may be of service to those engaged in the study of the drift beds of this district. As an illustration of what may be done by the employment of a good method, it may be mentioned that when the writer, in conjunction with his friend, Mr D. Robertson, commenced to deal microscopically with the glacial clays, only two doubtful species of Ostracoda had been observed as fossils in them. We have succeeded, however, in cataloguing 136 species, of which 19 are either now extinct or Unknown in the living state, and many are cf extreme rarity.[1]
The first essential point is thoroughly to dry the clay. This ought to be slowly done. The clay should not be placed in an oven or close to a
- ↑ See Monograph on the Post Tertiary Entomostraca of Scotland, by G. S. Brady, Rev. H. W. Crosskey, and D. Robertson. Published by the Palæontographical Society, 1874.