The curve of tree growth in California seems to be a true representation of the general features of climatic pulsations in the Mediterranean region. This conclusion was originally based on the resemblance between the solid line of Fig. 4, representing tree growth, and the dotted line representing changes of climate in the eastern Mediterranean region as inferred from the study of ruins and of history before any work on this subject had been done in America.[24] The dotted line is here reproduced for its historical significance as a stage in the study of climatic changes. If it were to be redrawn today on the basis of the knowledge acquired in the last twelve years, it would be much more like the tree curve. For example, the period of aridity suggested by the dip of the dotted line about 300 A. D. was based largely on Professor Butler's data as to the paucity of inscriptions and ruins dating from that period in Syria. In the recent article, from which a long quotation has been given, he shows that later work proves that there is no such paucity. On the other hand, it has accentuated the marked and sudden decay in civilization and population which occurred shortly after 600 A. D. He reached the same conclusion to which the present authors had come on wholly different grounds, namely, that the dip in the dotted line about 300 A. D. is not warranted, whereas the dip about 630 A. D. is extremely important. In similar fashion the work of Stein[25] in central Asia makes it clear that the contrast between the water supply about 200 B.C. and in the preceding and following centuries was greater than was supposed on the basis of the scanty evidence available when the dotted line of Fig. 4 was drawn in 1910. [Illustration: _Fig. 5. Changes in California climate for 2000 years, as measured by growth of Sequoia trees._ Fig. 5 is the same as the later portion of Fig. 4, except that the vertical scale has been magnified threefold. It seems probable that the dotted line at the right is more nearly correct than the solid line. During the thirty years since the end of the curve the general tendency appears in general to have been somewhat upward.]