N 







Microns 



30 



A 





«•- 1«i,: 







Microns 



10 



B 



FiGiRE 143. — Small picco of dark muscle fiber from tho contracted adductor muscle of C. virginicn. A — Whole mount 

 in glycerol after nitric acid treatment. B — Small portion of the same negative magnified. Round glol)ules are 

 artifacts. Phase contrast lens. 



156 



FISH AND WILDLIFE SERVICE 



