Pursuant to this deduction, we prepared pure amygdalin in the Krebs' laboratories in the 1940's, did comparative toxicity studies, found it non-toxic in doses appropriate to human and animal needs, and then proceeded to study the material clinically.

From the first, those of us involved in the clinical tests were aware that the *amygdalin molecule occurring in nature*, and common to human biologic experience in hundreds of edible seeds and plants, is unstable during and after extraction from its natural source. The slight variations in extracting procedure cause many of the amygdalin molecules to change to a form unknown to nature. These are known as isomers. Such a conformation is called neo-amygdalin. A mixture of natural amygdalin molecules and neo- amygdalin molecules is called isoamygdalin. This unnatural iso-amygdalin which is the result of poor extraction technique, caused unpredictable, often severe, reactions in our patients.