159 



Mr. PUTNAM on announcing the acceptance of the vote 

 alluded to the marked propriety of attaching the name of 

 Agassiz to so interesting a bowlder, and stated that here- 

 after, in all the publications of the Essex Institute, this 

 bowlder would be known by the name now bestowed, and 

 that in due time the name would be incorporated in works 

 upon the subject of glacial action in New England. 



Rev. Dr. BOLLES, of Salem, was the next speaker, and 

 took as his theme the reason why leaves change their 

 color in the autumn, and why it is when the time has 

 come that they fall from the trees. He explained that 

 these things were not occasioned by frost, as so many 

 suppose. Frost congeals foliage, rendering it flaccid, and 

 it takes on the color of decay. Nor is it any process that 

 comes from outside the leaf, but the result of certain 

 changes that take place in the leaf itself. The leaf is a 

 living thing, the workman of the plant, from which it gets 

 its growth, blossom, and fruit. Dr. Bolles then entered 

 into a minute description of a leaf, its framework and 

 covering, the vegetable cells, from which it receives its 

 color, and showed how, from some change in these cells 

 the leaf ripened and took on the glowing colors of autumn 

 foliage. He spoke of the assistance received in the study 

 of this subject from the spectroscope, an instrument so 

 powerful that it reaches and penetrates the mysteries of 

 the planets, yet so delicate as to take cognizance of the 

 chemistry of a tiny leaf-cell, unknown save as we analyze 

 it through this wonder-working glass. The doctor also 

 explained how, at the ripening of the leaf, a cork-like 

 substance is formed at the junction of the stem with the 

 twig, until the leaf is ready to fall at the slightest breath, 

 without the bleeding and loss which would ensue from the 

 violent disruption of the foliage from the tree. 



