124 BOARD OP AGRICULTURE. 



water, to whicli may be added a small amount of salt, oil of 

 anise-seed, or assafoetida. Sometimes decoctions of quassia, 

 worm-wood, or southern-wood (^Artemisia ahrotanurn) are 

 used for this purpose, with good results. To these a portion 

 of olive-oil may be added. But any remedy that may be em- 

 ployed must be repeated as often as once every three or four 

 days for at least three weeks, in order to destroy the young 

 ones as fast as they develop. An application of mercurial 

 ointment to the parts about the anus is recommended to pre- 

 vent the migrations of the parasites and the uncomfortable 

 itching sensations that they thus produce. 



The common Round-worm of 3Ian (^Ascaris lumbricoides 



Linn.). 



This species is well known as a parasite of the human in- 

 testine, especially in children, though often found in persons 

 of all ages. The round-worm of cattle is generally regarded 

 as the same species. 



These worms are round and smooth, tapering to both ends, 

 with a tough, elastic skin. The mouth is situated at the more 

 pointed end, and is provided with three prominent papillae, or 

 fleshy lobes. The male grows to the length of six inches, 

 and has the posterior end curved and provided with two 

 slender spicules. The female is much larger, sometimes be- 

 coming twelve or fourteen inches long and one-fourth of an 

 inch in diameter ; the female genital orifice is in advance of 

 the middle of the body. 



Development. 



The females produce great numbers of minute eggs, which 

 are provided with thick, rough shells. The eggs are dis- 

 charged and pass from the human intestine before the 

 development of the embryos commences. If kept 

 in water the embryos go on developing slowly and 

 gradually, the whole process requiring from six months 

 to nearly a year. The fully developed embryos are 

 round and slender, about xio of an inch long, with 

 an obtuse head and an acute tail. They have not been ob- 

 served to quit the eggs of their own accord, but may live for 

 at least a year within the egg-shell, after they attain their full 



