For the purposes of analysis some were divided into a “visceral” part and a “muscle” part, before being dried in an oven at about 55° C. Others were dried similarly without separation into parts, and some were used fresh for glycogen estimation. Protein. The usual method of estimating protein in food is to multiply the nitrogen by the factor 6.25 or 6.37. This method is based on the assumptions that most of the nitrogen is in the form of proteins, and that the proteins contain an average of about 16 per cent. nitrogen. Of these assumptions the first, at any rate, cannot be held without reserve in the case of these shell-fish, as the following figures show:— In one sample of dried paua, “visceral” part, the total nitrogen was found to be 9.0 per cent.; in another sample of the same powder the nitrogen present in an extract made with repeated quantities of strong alcohol followed by a small amount of watery trichloracetic acid was 2.95 per cent.; while that of the residue was 6.35 per cent. The figure 2.95 is due to substances of non-protein nature. If we were to proceed in the orthodox way to calculate the protein percentage from the total nitrogen we should get 58.1 (9.3 × 6.25), or about 15 per cent. of the fresh material. If, on the other hand, we were to take only the nitrogen that is insoluble when treated as described above we should get 39.7 per cent. protein (6.35 × 6.25), or about 10 per cent. of the fresh “viscera.” The true figure lies somewhere between these extremes, for some of the nitrogen of the extract may be due to amino acids split off from protein by autolytic changes in the earlier stages of drying, and such amino acids cannot be regarded as entirely valueless. The above figures refer to the “viscera.” A somewhat similar result is given by the “muscle” part, where the total nitrogen was 12.2 per cent. of the solids, and this consisted of 7.54 per cent. insoluble and 4.70 per cent. soluble in strong alcohol. In each case 30 to 40 per cent. of the total nitrogen was not in true protein form, and in such cases it is therefore incorrect to use the factor 6.25. Carbohydrate. Using Pflueger's method of estimation, we obtained the following figures for the glycogen percentage of freshly treated Haliotis iris:— Table II. Sample. Part. Weight in Grammes. Amount used (Grammes). Percentage of Glycogen. I Muscle 156 100 1.20 Viscera 104 104 0.54 II Muscle 160 100 2.01 Viscera 135 125 0.50 An attempt was made to obtain a clear watery extract for estimation of glucose, so that we might find the total percentage of carbohydrate present, but in spite of various devices the filtration proved so slow that the material began to decompose and had to be abandoned. The cause of