ANCYLOSTOMA DUODENALE 



45 1 



Development. The eggs are oval with broadly rounded poles, 

 to 6 1 fjb by 34 //, to 38/4. In fresh faeces they contain four 

 granular nucleated segmentation masses of the ovum (fig. 329) 

 separated by a clear space from the shell. 



Egg of Ancylostome appears to have a single contour. Under high 

 powers this appears double, but they are the outer and inner surface 

 of the true (chitinous) egg-shell. Internal to this is the extremely 

 delicate yolk-envelope, a kind of skin secreted by the egg cell around 

 itself for protection. The function of this is probably to absorb 

 water to swell and burst the outer chitinous shell. The embryos 

 when hatched are termed larvae 



Embryos which are ready to hatch have their bodies almost free 

 from granules ; others, though apparently mature, that have granules 

 will not hatch. 1 



FIG. 329. Ancylostoma duodenale : eggs in different stages of develop- 

 ment, a to c, in fresh faeces ; d, containing a larva, only in old fseces. 

 x 336. (After Looss.) 



Larva. Stage I : Average length, 25 mm. Maximum thickness 

 in cesophageal region, 17 p. Head end fairly blunt, from behind the 

 anus (the tail) tapering in an uniform manner. Buccal cavity is 

 characteristic, 10 //, to 12 p by i yu, to 8 //,, longer and narrower than the 

 corresponding larvae of Strongyloides stercoralis. (Esophagus " rhab- 

 ditic " in character, i.e., it has three sections, but they are not so clearly 

 marked off as in larvae of the genus Rhabditis. The posterior bulb has 

 a Y-shaped valve, the function of which, according to Looss, is to 

 prevent regurgitation of food. The granules of the gut serve as a 

 reserve of food, and are used up if the larvae are starved. The genital 

 rudiment consists of two cells half-way between the end of the 



1 TABLE OF DIFFERENCES BETWEEN LARV^: OF A. duodenale AND S. stercoralis. 



29 



