METAZOA VERMES. 313 



passed in the body cavities of insects ; afterward Gordius 

 becomes free in water, where it sexually matures. The 

 body of the adult (No. 775, Gordius varius taken from a 

 well) shows no vestiges of segmentation nor of distinct 

 regions. 



Ascaris ( = Angiostomum) (No. 776) is one of the 

 parasites of man, being found usually in the small intes- 

 tine. The eggs pass from the intestine and develop in 

 water or moist earth, and the larval life is spent in this 

 environment. It is not known how the larva reaches its 

 place of final development. The adult has lost its seg- 

 mented structure, also its locomotor and external respir- 

 atory organs. The body is more or less cylindrical and 

 tapers at both ends, the head not being differentiated. 

 The digestive system is present with the mouth in front 

 and the anus at the posterior end. In this condition the 

 animal is an hermaphrodite. No. 777 is a preparation of 

 a female Ascaris (A. lumbricoides) showing the intestine 

 and generative organs. The female is ten to fourteen 

 inches long, while the male is only from four to six inches 

 in length. 



Another Nematode worm, Filaria epinocaudata (No. 

 778) is parasitic in the seal, those of No. 778 being found 

 in the right ventricle and at the base of the pulmonary 

 artery of Phoca vitulina. The thread-like body is with- 

 out segmentation, distinct head, branchiae, or locomotor 

 organs. Filaria insignis (No. 779) was taken from the 

 foot of a raccoon. 



The guinea-worm of hot climates, Filaria medinensis, 

 passes its earliest stages in the water, but its later larval 

 life is spent in the little crustacean, Cyclops. The latter, 

 in drinking water, is swallowed by man. The parasite 

 then finds its way to the outer integument of its host, 

 where just under the skin of the leg or the shoulder it 

 becomes encysted. In time it matures sexually and pro- 

 duces living young which bore through the skin and find 

 their way to the water. 



