The Dibothriocephalus latus is not generally found except in districts bordering the Baltic Sea, the districts round the Franco-Swiss lakes and Japan.
In a number of cases there are colicky pains in the abdomen, with diarrhoea or constipation and more or less anaemia, while the Dibothriocephalus latus is capable of producing a profound and severe anaemia closely resembling pernicious anaemia.
The line FL perpendicular to the axis, G D and passing through the focus, is the semilatus rectum, the latus rectum being the focal chord parallel to the directrix.
The points in which the cutting plane intersects the sides of the triangle are the vertices of the curve; and the line joining these points is a diameter which Apollonius named the latus transversum.
At any point on the latus transversum erect an ordinate.