How does Bill Bryson use imagery in A Short History of Nearly Everything?

Imagery:

" After a few days, the water in the flasks had turned green and yellow in a hearty broth of amino acids, fatty acids, sugars and other organic compounds. 'If God didn't do it this way,' observed Miller's delighted supervisor, the Nobel laureate Harold Urey, 'He missed a good bet.' "

"The most enigmatic character of all was [Rosalind] Franklin. In a severely unflattering portrait, Watson in The Double Helix depicted Franklin as a woman who was unreasonable, secretive, chronically uncooperative, and - this seemed especially to irritate him - almost willfully unsexy. He allowed that she 'was not unattractive and might have been quite stunning had she taken even a mild interest in clothes,' but in this she disappointed all expectations."