A professor's ""natural history"" of American political parties which is concerned not only with the social or group composition thereof, but also with the part played by national political leaders in their formation and maintenance. The concentration is on the platforms, the points of view, the sectional representation, and the economic interests which motivated the voting groups as each party developed, came into power, and subsided, with opposition elements as the basis for each new major party. No traces the historical pattern from the Federalists and the formulating of the Constitution down to the Roosevelt development of present day democracy, and the conservative Republicans grown ""flabby"" from years without opposition. He prophesies a possible Republican cashing in on postwar reaction, a temporary rally unless the party can win the middle and lower income breshets. Thorough research and brisk presentation, rather than critical approach. A good piece of work -- and a useful one.