Abstract
1. The composition of the milk of six low-plane and six high-plane ewes has been studied. Definite lactational trends have been observed for all the major constituents.2. For all the ewes the initial colostrum was characterized by very high protein and fat contents and by low lactose content.3. Analyses of the mineral constituents—calcium, magnesium, sodium, potassium, phosphorus, and chloride—are reported covering the whole lactation of twelve sheep. The colostrum of the low-plane animals was higher in total mineral content than that of the high-plane animals.The author wishes to thank Mr L. J. Lambourne for providing the milk samples and Mr J. E. Allen for the spectographic analyses.