ORGANIZATIONAL UNITS 

 A C 



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FIG. 7. Various types of cells, highly magnified: A, female germ i-dl, egg of ;i Cut. 

 B, male germ cell, sperm of a Snake. C, three ciliated epithelial cells from the digestive 

 tract of a Clam . D, supporting tissue (cartilage) of a Squid. E, voluntary (striated) mus- 

 cle fiber from an Insect. F, involuntary (smooth) muscle fibers from the bladder of a Calf. 

 G, nerve cell from the brain of Man. (From Hegner, after Dahlgren and Kepner.) 



