The theory and practice of hygiene (Notter and Firth) revised and largely re-written / by R.H. Firth.

  • Notter, J. L. (James Lane), 1843-1923.
Date:
1908
Catalogue details

Licence: In copyright

Credit: The theory and practice of hygiene (Notter and Firth) revised and largely re-written / by R.H. Firth. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

    602/1096 (page 570)
    medinensis, is a parasite endemic in many parts of India, Persia, Arabia, Egypt, the West Coast of Africa, Demerara, the Brazils, and other tropical countries. The Guinea-worm disease is undoubtedly the same disease as the dracontiasis of Plutarch, and corresponds also with the IsraeHtish endemic affection described by Moses as due to fiery serpents. The curiously limited preva- lence of this parasite in certain districts was for many years inexphcable, until Pedschenko discovered the fact that a certain species of fresh-water Cyclops, having apparently a very capricious distribution, is a necessary factor in the life history of the filaria. Consequently, the distribution of the Guinea-worm is bound up with and dependent on the distribution of the particular species of fresh-water crustacean which, in reality, acts as its mtermediate host. _ . i -4.1, i-i,- JSTot only man, but oxen and some other animals, are aflectecL witn mia filaria or a parasite very closely allied to it. As yet, the female dracunculus alone is known with certainty, though Charles has described structures in connection with two female dracunculi which are suggestive of the male dracunculus in coitu. Immature specimens of Giiinea-worm vary m length from a few inches to as many feet. The mature worm is a long,^miiky- white, slender, cylindrical organism, having a thickness of about inch, and not at all unlike a thick fiddle-string. Its actual length varies from 1 to 12 feet. The head of the worm is short and tapering, terminating in an oval irregular surface called the cephalic shield. In the centre of this is a triangular buccal orifice, which leads to an alimentary canal, extend- ing along the whole length- of the creature, and endmg bhndly Close to the buccal orifice are two papHlae, with six others at the circumference of the shield; these are generally regarded as sensory organs. The posterior end of the parasite terminates in a blunt point which is often bent, like a hook, towards the ventral surface. Nearly the whole of the worm is occupied by a long, tubular, and embryo filled uterus. No trace of a vagina can be detected in the mature worm, though there is evidence to suggest that originally there was one. The emission of embryos appears to take place by the buccal orifice. _ Like many other animal parasites, its presence m the tissues of man is but a portion of its life history,_ and to complete its cycle of existence it requires to pass into the tissues of some other living organism. The worm, having gained access to man's body, probably m a larval form, fying in the body of the cyclops, bores its way mto the tissues. When or where the sexes come together and what are the subsequent steps in the development ot the female, and what becomes of the male worm, are unknown. After an interval of from nine months to a year, a stage of maturity appears to be reached, as indicated by the pre- sence of a worm many inches in length, embedded in the cellular tissue of the host, with an enormously developed Fig. 101.-^m- ^ . J .^li^^^^ embryos. The embryo which J;7o™^ arrfeSed from man is. aquatic in ^f^^f^^^^^^^:, Bastian). develop needs to pass into water. In size the embryos 1 W 1 of an inch. They are distinctly flattened, tapenng r'nlSs tXSrJ, and ei'minatiJg posteriorly in a long, slender^ s^ptpo'^e^^^^^^^^ 101). They are very active, swimming about like