42 GUIDE TO THE .STUDY 



Compare with the demonstration of the head capsule of Ancy- 

 lostoma duodenale of man, noting especially differences in the 

 paired teeth. 



Study also the demonstration of the buccal capsule of Necator 

 americanus (Fig. 16) and note the two chitinous plates which 

 replace the ventral teeth found in the genus Ancylostoma. The 

 latero- ventral pharyngeal plates and the dorsal pharyngeal tooth 

 also differ in this genus. 



Development. — Make drawings of various segmentation stages 

 of the hookworm eggs from feces. 



Make a careful study of the sheathed infective larva. If 

 living material is available, note the movements and combine 

 study of the living and the mounted worms. Make a drawing 

 showing the buccal cavity, oesophagus, intestine, genital pore, 

 genital rudiment, and anal opening of the larva. 



Penetration of the Skin by Hookworm Larvae. — Examine 

 the demonstration showing a section of skin and of a larval 

 hookworm which has penetrated its outer layers. 



Soil Nematodes. — Examine a preparation of living nematodes, 

 isolated from garden soil by the use of the Baermann apparatus, 

 and distinguish the hookworm larvae. 



References 



The standard textbooks on parasitology — Braun, Brumpt, Chandler, 

 Faust — and such sources as the "Reference Handbook of Medical Science" 

 afford easily accessible discussion of the morphology and biology of the 

 hookworms of man. For references to more special papers, see the "Bibli- 

 ography of Hookworm Diseases" issued by the International Health Board, 

 1922. 



