The _Heteroura androphora_ is another nematode which lives in the stomach of tritons. The male is always rolled round the body of its female. The two sexes are always free, contrary to that which is observed in the syngami. The Blattæ, coleopterous insects, also harbour sexual nematodes. Radkewisch saw two species of anguillulæ, the _Anguillula macroura_ and _appendiculata_, in the _Blatta orientalis_, and an _Oxyuris brachyura_ in the _Blatta germanica_. These eggs leave the body with the feces, and resist the action of deleterious agents. _Heterodera Schachtii_ is the name given to a nematode which Mons. Schacht discovered on beet-root. This is also a dimorphous worm; the male has the usual form, the female resembles a lemon. The _Leptodera appendiculata_ inhabits the foot of the _Arion empiricorum_, in the larva state, and becomes sexual (male and female) in the decomposed body of the snail. The next generation has the sexes united, and lives in damp earth. The _Leptodera pellio_ lives in the same way in the bodies of lumbrici; another Leptodera inhabits the intestine of the snail, and a third the salivary glands. The nematode so generally known under the name of _Ascaris nigro-venosa_ also belongs to this genus. It lives in the lungs of the frog. There is one also in the lungs of the toad, but it differs from the preceding. Leuckart looks upon these worms as females, and their reproduction as parthenogenetic. Schneider considers that the male exists by the side of the female sex, and that they are consequently hermaphrodites. These worms in the lungs are viviparous, and embryos are found in 249 the midst of the intestine of the same animal which gives lodging to the female. These same worms, proceeding from an hermaphrodite parent, or from parthogenetic females, live at liberty, and not parasitically in damp earth or in a decomposed body, and differ from their parents in size as well as in sexual organs. They all become either male or female, and consequently their fecundity is dependent upon copulation. Their parents could all multiply without it, but they cannot. The females alone produce a new generation. A worm known by the name of _Vibrio anguillula_ lives in grains of corn while still green, and multiplies there to a prodigious extent; it is this which causes the disease known by the name of smut. The grains grow hard, and enclose nothing but little dried worms, which remain thus without apparent life, yet without dying, until they are moistened, when they become damp, the tissues swell, the organs resume their natural appearance, and the functions are restored at the end of a few hours.