56 



How would you proceed to examine an Earthworm for 

 Monocystis agilis ? 



Open the earthworm (under salt solution) from the 

 ventral side. Slit open a seminal vesicle, remove some 

 of the fluid contents with a pipette, place a drop (diluted 

 with salt solution) on a microscope slide, and, placing a 

 coverslip on top, examine under the microscope. 



Having mounted a Drop of the Earthworm's Seminal Vesicle 

 Fluid, describe what you would probably see. 



The fluid would consist chiefly of countless minute 

 hair-like spermatozoa, and many floating mulberry-like 

 clumps called sperm-morulse, each a cluster of developing 

 spermatozoa attached by their heads to a central piece 

 of protoplasm. Amongst the sperms and sperm-morulse, 

 there would probably be some trophozoites with or without 

 furry coats composed of the tails of destroyed sperms ; 

 and almost certainly large spherical cysts would be seen, 

 full of small ovate spores (pseudonavicellae), also numbers 

 of these spores scattered about from burst cysts. Pos- 

 sibly a cyst of another kind would be noticed, one con- 

 taining two large oval masses (gametocytes) joined together ; 

 and also perhaps gametocytes in associated pairs but not 

 yet encysted. 



KEY TO FIG. 12 



A. Three trophozoites. 



B. Cyst containing two gametocytes. 



C. Stage prior to formation of gametes. Note the numerous small 



nuclei. 



D. Gam'etooytes broken up and gametes formed. Some of the 



gametes are conjugating in pairs ; some pairs have fused 

 to form zygotes. 



E. Cyst containing ripe spores or pseudonavicelta. 



F. A single spore or pseudonavioella containing falciform sporo- 



zoites. 



G. A sporozoite inside a spem-morula. 



H. A young trophozoite coated with tails ot destroyed sperms. 



