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ment for only a short distance. In others (Figs. 47, 49, 50) one 

 projection from a rather broad based cone rises around the fila- 

 ment as a fairly narrow process. In still other eggs (Figs. 48a and 

 e, and 51) a very slender projection creeps up the acrosome fil- 

 ament for some distance and surrounds it in a sleeve of proto- 



Fig. 47. Successive stages of sperm entry in Tinjone hriareus, from 

 sketches of a living specimen. (From Colwin and Colwin, Biol. Bull., 

 1956.) A broad cone with filose projections elevated one moderately slender 

 sleeve of protoplasm around the inmoving acrosome filament. Acrosome 

 filament seen in outer part of cone: solid Line. Presumed further course of 

 filament: dotted line. 



plasm so narrow as to make this portion of the cane itself seem 

 like a filament. ( 2 ) The acrosome filament can sometimes be seen 

 within the hyaline cone (Figs. 48a-e and 49-51). Failure at 

 other times to see the filament within the cone was attributed 

 to optical conditions since often the even much thicker flagellum 

 could not be seen within the cone. (3) While areas beneath the 

 egg surface were vety difficult to observe, nevertheless in a few 



