Nitrogenised principles of food are subservient to the formation of albumen, whilst the non-nitrogenised are mostly converted into fat or oil. The fact, that a union of these is essential to nutrition, is explained, according to the chemist, by supposing that albumen constitutes the basis of the tissues, and that oil furnishes the elements of respiration and animal heat. This theory, however, does not explain the origin and maintenance of all growth, which is so essential to the vital functions. The author considered that the necessity of oil and albumen was accounted for by their being both necessary to the formation of the tissues, and he endeavoured to shew that there is no elementary cell into which these principles do not enter as constituent parts.