ANCYLOSTOMA 



669 



can be seen coiled up in the egg, from which it escapes as 

 and feeds on the faecal material. The larva is needle-shaped, 

 posteriorly, and measures 200 to 250 ^ in length 

 by 15 to 17 /J, in breadth, and is rhabdite in 

 form, with a long cylindrical terminal mouth, 

 opening into an oesophagus, which, after narrow- 

 ing, swells out into a bulb with three valves. The 

 straight intestine surrounded by granular 

 material opens into an anus situate some dis- 

 tance in front of the tip of the tail. This larva 

 undergoes a first ecdysis when it becomes 

 narrower, and the oesophagus and mouth lose 

 their characteristic appearance, while it forms 

 a new skin inside the chitinous cuticle, so that 

 (at the end of five days in the tropics) it now 

 ceases to grow and feed, and takes to water or 

 moist earth, where it can remain unchanged for 

 months, living on the food-material enclosed in 

 its own cells (stage of encystment). During this 

 condition it may be quite active, and can swim 

 and climb up any surface which is wet. This is 

 an important factor in explaining the production 

 of certain kinds of skin eruptions. It is now 

 ready to infect man, which it does through the 

 hair-follicles of the skin, causing eruptions or 

 sores — e.g., ground-itch. 



From the hair-follicles it forces its way via the 



a larva, 

 pointed 



DuBiNi: Female. 

 (After Looss.) 



Fig. 293. — The Median and External Caudal Fig. 294. — Ancyio 

 Bursa of Ancylostoma duodenale Dubini. stoma duodenal/ 



I, Costa dorsalis; 2, costa dorsalis externa; 3, costa 

 lateralis posterior et externa; 4, costa lateralis 

 media; 5, costa ventralis. 



(After Railliet, from Stiles's Report.) 



subcutaneous tissue into the venous bloodvessels and lymphatics. In 

 the] former it [reaches the right heart and the lungs easily; in the 



