MANUAL OF NATURAL HISTORY 349 



of organization than the "Vers parenchymateaux" 

 of the same illustrious savan. Together these two 

 types of structure constitute the Entozoa of many 

 authors, from the greater number living in the in- 

 testines and other internal parts of various animals. 

 In these higher forms, nervous fibres connect the 

 different organs of the body by a common sym- 

 pathy ; the muscles become more apparent and as- 

 sume greater energy; the alimentary tube is en- 

 closed in walls of its own, and not simply hollowed 

 out of the tissues ; it, moreover, possesses two dis- 

 tinct orifices, an oral and an anal ; and the sexes 

 are separate in different individuals. The bodies 

 of these parasites are worm-like, long, elastic, and 

 cylindrical, are never provided with limbs or organs 

 of locomotion, while the only sense they seem to 

 possess is that of touch. They obtain their food 

 by dwelling always parasitically in the bodies of 

 other animals, subsisting on their juices. Among 

 these by no means attractive members of the king- 

 dom of animals we find the Guinea worm (Filaria 

 medinensis), which burrows beneath the skin, and 

 sometimes grows to several feet in length ; the As- 

 caris lumbricoides, which lives upon the substances 

 of the intestinal canal already elaborated for it by 

 man and quadrupeds ; the Opkiostoma, which in- 

 habits the air-bladders of fishes ; < and others are 

 found in the various localities selected by different 

 members of this tribe of beings. One of the most 

 anomalous among them is the ISyngamus trachealis, 

 in which the male is organically blended with the 



