24 



Brierlev, Life-Histfljy of LeptosphcBJ-ia Levtanece. 



PLATE II. 



Figs. 1 6- 1 8. — Stages in perithecial development. 



Fig. 1 6. — The deeply stained ascogenous elements are sur- 

 rounded by the sterile thin-walled tissue. x i,ooo. 



Fig. 17. — The perithecial neck has commenced to form, and 

 the sterile tissue around the ascogenous elements is 

 collapsing. x i',ooo. 



Fig. 18. — The perithecial neck is formed and the asci have 

 enlarged and become uninucleate. x 1,000. 



Figs. 19-22. — Stages in the destruction of the host nucleus 

 and cytoplasm. 



Fig. 19. — The nucleus of a normal host cell, x 2,000. 



Fig, 20. — The nucleus of the lower cell still possesses its 

 nucleolus and nuclear membrane ; whilst in the 

 upper cell the former has disappeared and the latter 

 is indistinct. x 2,000. 



Fig. 21. — The nucleus has lost both nucleolus and membrane, 

 and the cell protoplasm has degenerated, x 2,000. 



Fig. 22. — The cell contents have almost completely disappeared, 

 and the walls are shewing mucilaginous degeneration. 

 X 2,00c. 



