800 RECOKD OF CURRENT RESEARCHES RELATING TO 



the skin excretes a transparent chitinous substance, forming a capsule 

 which encloses the whole animal, allowing of its free movement 

 within. Now the mouth develops the rudiments of its hooks and 

 styles ; the intestine becomes less granular and more transparent ; 

 between two of the middle segments appear the papillae which occur 

 on the sides of the perfect worm. The space left in the capsule round 

 the worm gradually diminishes, and, chiefly at the end, calcareous 

 corpuscles are excreted, of round, rectangular, &c., shape, forming a 

 protective crust. The acid of the gastric juice dissolves the coat and 

 leaves the larva free ; but death occurs if it does not reach a human 

 body ; in the encapsuled state it resists desiccation and the action of 

 indifferent fluids for twenty-fom* hours, and lives well in clear or 

 muddy water ; a single drop of water may contain 100 larvae. 



Larval Development of Anguillula intestinalis. — The eggs are 

 oval, with more pointed poles than in Ancliylostoma ; they measure 

 • 05-* 06 mm. by • 03-" 036 mm. Development progresses well at the 

 temperature 25° to 26'' C. ; bii*th takes place in from fourteen to 

 twenty hours ; the embryos are more clearly visible, and move more 

 vigorously within the shell, than in Anclujlostoma. A short quiescent 

 stage ensues on birth, followed by active movements ; the length of 

 the larva is -2- -24 mm., the diameter -012 mm.; it is slightly 

 attenuated in front and has a very sharp tail. The head is trilobate, 

 the mouth rectangular, with a pharynx and pharyngeal bulb ; the 

 intestine is cellular and zigzag ; a genital rudiment exists in the same 

 position as in Anchylostoma. The larvae need a liquid medium more, 

 and die if the mass becomes somewhat dry, showing a fatty breaking- 

 down of the tissues, but live in distilled or common water and in 5 to 7 

 per cent, solutions of common salt or sulphate of soda. In a liquid or 

 semi-liquid medium the larva doubles its length in twenty-four hours, 

 becoming -016 mm. thick; the head is round, the body cavity is 

 surroimded by the dermo-muscular layer, which secretes a most 

 delicate chitinous capsule for the body. 



Anguillula stercoralis Bavay, development of larva outside human 

 body. — The larvae are developed in the maternal uterus and are ex- 

 pelled with the faeces at diiferent stages; they are then free and 

 active, measuring •2-- 26 mm. by • 014-- 016 mm.; the anterior end 

 of the body is larger, the mouth shorter, the pharynx shorter and 

 broader, the intestine longer and wider than in the same stage of 

 Anchylostoma. The genital rudiment is very characteristic, being 

 shuttle-shaped and • 025 mm. by • 003 mm. in size. Encapsulation 

 generally takes place in a day. Experiments with different tem- 

 peratures proved that the larvae always exhibited movements within 

 five seconds at a temperature of 50° C. 



Facts show that these worms were alone sufficient to cause the 

 disease of aneemia observed at the St. Gothard tunnel ; the disease 

 probably resulted from the unfavourable conditions under which so 

 many poor workmen were engaged together. 



Anguillula intestinalis should be removed from that genus, and is 

 better named Slrongylus papillosus, the reasons for which change of 

 name are reserved. 



