Polar Bodies 



87 



separation of the polar bodies undoubtedly prepares 

 for fertilization, though their precise meaning is not 

 certainly known. It is generally held that by their 

 formation the substance of the female pronucleus is 

 reduced to the same extent as that of the male pro- 



^2 



Fig. 57. — A. Egg of Plant-bug (Pyrrhocoris) showing extruded polar bodies 

 (/>!,/> 2) and union of male (;«.) and female (_/".) pronuclei. B. Later stage 

 showing re-absorption of the polar bodies (;t i, / 2) and first division of the 

 segmentation nucleus. Magnified 35 times. After Henking, Zeits. wiss. 

 Zooloe., vol. 54. C. Parthenogenetic egg of Aphid showing the single polar 

 body (/.) and the nuclei («. n.) arranging themselves around the margin of 

 the egg. Magnified 580 times. D. Section through margin of egg of Blow- 

 fly, showing nuclei («. n.) surrounding the yolk (y.). E. Later stage show- 

 ing formation of distinct cells of the blastoderm (3/.). Magnified 200 times. 

 After Blochmann, Morph. Jahrb., vol. 12. 



nucleus, so that the contribution of the two parents 

 towards the segmentation nucleus may be equal. 



