the recent This pairing is strongly supported by all sources results5, which show thnt for of acid examin tho amount the of deoxyribonucleic thymino, and adenine is close to the amount of cytosine, amount of guanino close to the amount 1 although the cross-ratio (the ratio of adenine to vary from one source to another. guanine) can of bases on one chain is Indeed, if the sequence these analytical irregular, it is difficult to explain we have results except by the sort of pairing suggested.