A study of certain digestive glands in experimental animals (Langstroth, McRae and Stavraky 1938) required the analysis of samples of secretion, ranging from less than 1 to 15 c. c. in volume, for several different substances. The use of the quantitative spectrographic method of analysis for Na and K described in this article aided considerably in obtaining the data for each sample, and so resulted in a description which was relatively complete as compared with that obtained under a purely chemical procedure. This more complete knowledge of the composition of the secretions was found to be of the utmost importance in the interpretation of the results, and in obtaining an understanding of the behaviour of the glands. The method of analysis for Na and K, like that for Pb described in paper I (Foster, Langstroth and McRae 1935), depends on the determination of the intensity ratio of a chosen line of the investigated element to one of an internal standard element. In contrast to the method of paper I, however, the sample is excited in a condensed A. C. spark discharge, and use is made of a standard working curve, viz. the intensity ratio plotted against concentration. Some important features of the procedure are as follows. ( a ) The load placed on the electrode contains a fixed “large” amount of some suitable added salt (the buffer). This serves to obviate variations in the operation of the source due to variations in the composition of the samples. It permits the use of one working curve in the analysis of samples which vary considerably in composition. ( b ) The sample may be placed directly on an electrode previously prepared by drying on it a solution containing the buffer salt and internal standard. With this procedure only 0·01 c. c. of a sample is required for an analysis of both elements,( c ) The spectrum of each sample is photographed with an antimony absorption step-weakener (Langstroth and McRae 1937) before the spectrograph slit. The photographic blackenings of investigated lines then lie in the normal exposure region in some steps, and can there be accurately measured. In this way one exposure is sufficient for the determination of both elements, or of several elements if required.