The composition of the extracellular polysaccharides of Aerobacter-Klebsiella strains.

2. In the early stage of fat synthesis the fat is more acidic and contains a larger percentage of unsaponifiable substances than at any later period. 3. Until the stage of maximal activity of the mould is attained the actual amounts of both saturated and unsaturated component acids continue to increase, but in the subsequent phase ofthe life of the culture the weight of each of these components diminishes. 4. The results are not in accord with the hypothesis that, for the biosynthesis of fat, unsaturated acids are provided by dehydrogenation of saturated acids.