UNCINARIA AMERICANA 331 



rent ; this'occurs on the seventh day, when the animals are provided 

 with a provisional oral capsule which was not present previously. At 

 the end of this second period the definitive oral capsule with the 

 chitinous teeth is formed, and alterations in the position of the 

 genital glands, in the intestine, &c., set in, and on the completion 

 of the second ecdysis, which takes place on the fourteenth or 

 fifteenth day, the worms have attained their definitive organisa- 

 tion. Their length then averages 1*9 mm. (male) and 2 - o mm. 

 (female) ; three weeks after infection, however, the males in the 

 dog have already attained a length of 8 mm., and therefore we 

 may conclude that maturity is attained in about four or five 

 weeks. 



Recently Looss has discovered a second means of entrance of larvae of 

 Ankylostoma in the human body, which is THROUGH THE SKIN ; the larvae 

 placed on the skin with a drop of water penetrate the hair follicles in a 

 short time, andj leaving these in the vicinity of the hair papillae thus 

 attain the corium.- The author concludes that the larvae then find their 

 way into the lumen of the intestine, and is of opinion that this mode of 

 infection at all events as regards the fellahs has a far greater importance 

 than the infection per os. We must, however, await the proofs of this 

 statement, 



Uncinaria (=Anchylostoma) Americana, Stiles, 1902. 



[In May, 1902, Dr. Stiles discovered that uncinariosis in America 

 was not, as a rule, due to the old world hook-worm, Uncinaria 

 duodenalis, but to a new species which he named Uncinaria 

 Americana. 



Uncinaria Americana can be readily distinguished from Uncinaria 

 duodenalis. It is shorter and more slender. The male worm 

 measures from 7 to 9 mm. in length by 0-3 to 0-35 mm. in diameter ; 

 the female 9 n mm. in length by 0-4 0-45 mm. in diameter. 

 The buccal capsule is much smaller ; and presents an irregular 

 border ; instead of four ventral hook-like teeth, it is provided 

 with a ventral pair of prominent semilunar plates similar to those 

 of the dog hook-worm, Uncinaria stenocephala , the pair of dorsal 

 teeth is likewise represented by a pair of slightly developed 

 chitinous plates of the same nature. The outlet of the dorsal 

 head-gland, usually called dorsal rib or dorsal tooth, projects 

 prominently into the oral cavity. Deep in the buccal capsule are 

 one pair of dorsal and one pair of ventral submedian lancets. 



The caudal bursa of the male presents a short dorso-median 

 lobe, which often appears as if it were divided into two lobes. 



