KING COHN by Bob Thomas. 381 pages. Putnam. $6.95.
Gazing at the miles of neighboring urban sprawl and walking through the TV treadmills of Desilu and Warner's, the casual visitor to Hollywood will find it difficult to believe that it was once the habitat of Cro-Magnon man. His name was Harry Cohn, president and production head at Columbia Studios, and he flourished during the movies' Pleistocene epoch—circa A.D. 1930-58—subsisting on the backbones of executives and the egos of movie stars. When he died in 1958, more than 2,000 people turned out for his funeral,...