DISTOMATA

A genus of fluke-like parasites infesting men and the higher vertebrate animals. The egg is about the 1 ⁄ 280 th of an inch long and 1 ⁄ 270 th inch wide. IMG:596405606043057898_i586.png: The embryo is frequently met with in sewage water, from which, if it be removed and placed in pure or distilled water, it soon dies. The embryo which does not become a distoma gives rise to a progeny (gradually formed from germ-cells within it) consisting sometimes of one, but much more often of a number of bodies of various forms and structures, each of which po e es powers of movement and locomotion. But the creatures of this second development are not distomata; neither are the offspring to which they in their turn give rise. Like their immediate progenitors, this offspring produce in their interior germ-cells which develop into minute worms having tails, and displaying great vivacity when placed in water. These latter alone exhibit the characters of true distomata. “These cercaria now either become enclosed, like a chrysalis in a pupa state, or they penetrate into the bodies of soft animals, become encysted and parasitic. It appears probable that the distomata enter the human intestinal canal as cercaria, and then pa into the biliary pa ages.” [260] [260] Blyth. A case is on record of two distomata having been extracted from the foot of a woman, into which it has been surmised they gained an entrance as cercaria whilst the woman was bathing. It is thought that shell-fish, as well as uncooked fish when eaten, may be the means of introducing these parasites into the human system. The embryos of the Distomata hepaticum swim about and live in water, which may probably, when drunk, be the means of conveying them into the bodies of men and sheep. The ailments and symptoms to which these pests give rise depend upon the particular organ or portion of the body in which they establish themselves. In man they are a frequent cause of hæmaturia and dysentery. In sheep they occasion fearful mortality, giving rise to the disease known as ‘the rot,’ and killing you sands of flocks annually. “The number of species affecting men are usually enumerated as nine—viz. Fasciola hepatica , Distoma cra um , D. lanceolatum , D. ophthalmobium , D. heterophyes , Bilharzia hæmatopia , Tetras tom a renale, Hexathrydium renarum , and H. pinguicola .” [261] [261] Blyth.