PLATE 4 
EXPLANATION OF FIGURES 
Campanotus herculeanus var. pennsylvanica 
20 Outline of the first zone of differentiation, showing the membrane, m, 
separating it from the terminal chamber, and the oocytes, 0, nurse cells, n, and 
epithelial cells, e. The numbers 21, 22 and 23 refer to cells shown enlarged in 
figures 21, 22 and 23. X 620. 
21 An oocyte from the first zone of growth. X 3300. 
22 A nurse cell from the first zone of growth. 3300. 
23 An epithelial cell nucleus from the first zone of growth. X 3300. 
24 The posterior portion of the first zone of growth and the anterior portion 
of the rest of the ovariole containing bacteria-like rods. e, epithelial cell 
nucleus; n, nurse cell; 0, oocyte. X 1250. 
25 Part of an ovariole showing two oocytes, C; and Cs, in Stage C. mn, nurse 
cell. XX 1250. 
26 AnoocyteinStage D. The bacteria-like rods have invaded the cytoplasm 
of the oocyte. X 1250. 
