[To face p. UK. 





>*••:«* 









Fig. 97.— A Photomicrograph showing the Completely Matured 

 Umbryo-sac of Helhhorvs. The structures to be made out are the 

 central definitive nucleus, the synergidse and egg-eell at the upper 

 end, and three antipodal-cells at the lower end of the sac. 



