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Description of Plates 

 Plate I. 



Fig. 1. Diagrammatic sketches showing the development of a spermato- 

 zoon from a spermatogonium. 



Fig. 2. Diagrammatic sketch showing the minute structure of a sper- 

 matozoon. The middle piece is made comparatively thick in 

 order to bring out the finer structures. Adapted from 

 EUenljerger. 

 Plate II. 



Fig. 3. Testicle of bull, showing extensive degeneration and necrosis. 



Plate III. 



Fig. 4. Inner part of wall of ductus deferens. Normal, x 230. 



Fig. 5. Same, Imt showing extensive degeneration and exfoliation of 

 the lining membrane, x 230. 

 Pt-Atb IV. 



Fig. 6. Ductus deferens, showing entire exfoliation of the lining mem- 

 brane. The lumen is filled with a cellular debris, x 50. 



