HOOKWORMS 



325 



taking origin from the pharyngeal lobes. The collar-like mouth orifice is made up of 

 22 rounded plates just inside the round mouth opening. They are less than ^ 

 inch long and have once been found in the intestinal canal. 



(Esophagostoma brumpti. Six young females were found in a cyst of the colon in 

 an African negro. They were about > inch (8 mm.) long. The anterior end pre- 

 sents an ovoid protuberance with a second cuticular inflation just below it. The 

 buccal capsule is very shallow and surrounded by about a dozen chitinous plates. 

 The mouth has six papillae. 



This species has recently been reported by Thomas in a native of Brazil. 



Physaloptera caucasica. Mouth with two equal laterally placed lips, each hav- 

 ing three papillae and three teeth. The male has a lancet-shaped posterior extremity 

 and is about % inch long (14 mm. by 0.71 mm.). Female is about i inch long (27 

 mm.) with a rounded tail end. Found only once in the alimentary canal of a 

 native in the Caucasus. Leiper has recently reported a species P. mordens from 

 Uganda, one case. 



THE HOOKWORMS OP MAN 



The hookworm infections of man come almost entirely from two 

 parasites, Ancylostoma duodenale, the Old World species, and Necator 

 americanus, which is generally called the New World species from its 

 having first been reported from the U. S. by Stiles. Hookworms 

 belong to the class Nematoda and family Strongylidae. 



Quite recently Lane has reported a new species, A. ceylanicum, as having been 

 obtained from three men in Bengal, after treatment. This species is the one that 

 infects the civet cat in Ceylon. So far as we know the other human species belong 

 solely to man. 



The male hookworms are a little more than J inch (9 mm.) 

 long and the females a little more than J^ inch (13 mm.) in length. 

 The males can readily be distinguished by their posterior, umbrella-like 

 expansion or copulatory bursa. The tail of the female is pointed. The 

 vulva of A. duodenale is located in lower half of the ventral surface; 

 that of N. americanus in upper half. The large, oval mouth of the Old 

 World hookworm has four claw-like teeth on the ventral side of the buc- 

 cal cavity and two knob-like teeth on the dorsal aspect. It also has a 

 pair of ventral lancets below the four ventral teeth. One cannot make 

 out a dorso-median tooth. In N. americanus the buccal capsule is 

 round, smaller and the ventral teeth are replaced by chitinous plates. 

 Dorsally there are two similar but only slightly developed lips or plates. 

 A very prominent, conical dorso-median tooth projects into the buccal 

 cavity. Through it passes the duct of the dorsal cesophageal gland. 

 There are also four buccal lancets. The copulatory bursa of the Necator 



