29 LUMBRICUS 



To make the observations under 7, 8, 9, 10 it will be necessary to use a worm which has been opened under 

 75 per cent, (normal) salt solution. 



7. Nephridium removed and seen under low power : nephrostome ; glandular part ; blood capillaries ; muscular 

 discharging part. 



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8. Ovary under low power: immature ova; ripe ova. 



9. Place a drop of the contents of a seminal vesicle on a coverslip and fix at once with 90 per cent, alcohol. 

 Wash gently with 70 per cent, alcohol, then with 50 per cent, alcohol. Place coverslip in watch glass containing 

 picrocarmine for 15 minutes. Wash in water and mount in dilute glycerine. Sketch various stages of development 

 of spermatozoa. 



10. Treat a drop of the contents of a spermatheca as in 9. Sketch ripe spermatozoa. 



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