26 



LUMBRICUS 



4. Pin the animal, ventral surface downwards, by two pins through the clitellum and two through the sides 

 of the fourth segment. Stretch the body as much as possible. Open the body by a cut along the dorsal middle 

 line from segment 20 to segment 2 : fix the cut body-walls to the dissecting trough by pins on each side : septa ; 

 nephridia ; pharynx ; supra-pharyngeal ganglia ; oesophagus ; vesiculce seminales in segments 9 to 12 ; spermathecce 

 in segments 9 and 10 ; crop; gizzard; intestine; dorsal blood-vessel ; pseudo-hearts in segments 7 to n. 



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