Aqueous solutions of tobacco mosaic virus are ideal systems for visualizing distributions in the nematic phase by freeze-fracture electron microscopy. The order parameter in well aligned regions is measured to be greater than 0.9. Twist deformations appear to be most common, confirming that the twist elastic constant is smaller than either the splay or bend constants. Edge and screw disclinations are observed in tobacco mosaic virus nematics in configurations predicted by continuum theory. Disclination cores have been observed for the first time.