METHODS

Nomenclature. The very large number of acids of different chain lengths and double-bond contents which are now demonstrable by gas-liquid chromatography necessitates a shorthand designation. In this report fatty acids are numbered according to chain length (number before colon) and double-bond content (number after colon). Thus, 18: 0 refers to the normal saturated C1i acid, stearic; 18: 2= C18 diene, and so forth.'Wherever definitive informationon double-bond structures is avail-able, it would be more appropriate to specify the exact structure, ie, octadeca-9, 12-dienoic acid (or linoleic acid), but when this is lacking, acids are called dienes, trienes, and so on. The weight percentage compositions of fatty acid mixtures are called fatty acid patterns. Metabolic ward procedure. The subject of this study was a 23 year old white para III whose pregnancy was normal with spontaneous delivery at term. 2 She had mild chronic spastic colitis limited to the rectosigmoid colon for one year. The patient and her normal new-born daughter were admitted to this hospital on the fifth postpartum day and remained in the rooming-in unit of a metabolic ward for seven weeks' study. This metabolic ward has been described in detail elsewhere (1). The mother was ambulatory but sedentary. The baby was exclusively breast fed, six feedings per day at four hour intervals. Both were weighed daily under standard conditions. Feedings were successively initiated at alternate breasts, and both were offered at each nursing. The mother was nourished solely by an orally administered liquid formula, the total daily intake being divided into five equal portions, supplemented with vitamins and minerals as previously described (7). Water was offered ad libitum. The mother's intakes exceeded