Total nitrogen and amino acids were determined in 44 kinds of Japanese lichens ; the former by the semimicro-Kjeldahl method and the latter by amino acid analyzer (Hitachi Model KLA-2). The number of amino acids detected in these lichens was 10 at the minimun and 20 at the maximum. As in the previous work, content of alanine and glutamic acid was larger than those of other amino acids in the present 44 kinds of lichens ; those containing more than 100μmole/100g of lichen being ca. 40.91% for alanine and ca.16.64% for glutamic acid. Summarizing the total of 144 kinds of lichens reported in parts I to III, lichens containing more than 100 μmole/100g, were ca.45.2% for alanine and ca.17.4% for glutamic acid. Quantitative determination of amino acids was made with Dermatorcarpon miniatum (L.) MANN and it was found to contain the highest amount of giycine, asparticacid, proline, arginine, lysine, methionine, and cysteic acid, next highest content of leucine, serine, threonine, glutamic acid, histidine, and taurine, and third highest content of alanine and valine among the 144 kinds of lichens examined. This lichen contained a total of 18 kinds of amino acid and, together with the above high contents, this lichen must be a unique one. Amino acid-nitrogen, calculated from the analytical values of amino acids, became ca.0.2% against total nitrogen value of 2.32%, and the remaining ca. 91.19% must be due to other nitrogen-containing compounds. Total nitrogen was especially high in 2 kinds of Peltigera and 1 kind of Sticta. Total nitrogen of 4.47% was found in Leptogium tremelloides S. GRAY var. azureum NYL., which is second to 4.52% in Peltigera variolosa (MASS, ) GYEL., and 10 of 18 kinds of amino acid contained were in more than 100mole/100g of this lichen. Other lichens of Leptogium sp. may also show the same result and this lichen is also an interesting one. It was also of interest that 8 kinds of Usnea sp. contained taurine. The lichens examined were found to contain a few kinds of Ninhydrin-positive substance, other than amino acids constituting the protein, as was found in previous work, but the substances were not examined further.
