240 THE PLANT WORLD 



to the line separating the limestone from the volcanic rocks. Here the 

 limestone was metamorphic and there were no vestiges in it of fossils, 

 and in several places Dr. Maj^er broke off masses of crystalline calcite. 

 He said that the calcination of the limestone showed it to have been 

 heated since its elevation. It was not a question of the elevation of a 

 mass of coral which had formed about a submarine volcanic peak, but of 

 a volcanic eruption after the mass had been elevated. There was no 

 evidence of recent volcanic action, and unlike Mount Santa Rosa, no 

 vestige of a crater. On the slope of the mountain I collected some ferns 

 (Gleichenia, Lindsaya, and Pteris) and a tiny yellow-flowered Hypoxis. 

 In going through a patch of sword-grass {.Miscanthus Jioriduliis) I cut 

 my hand in spite of precautions. With a lens I could see that the 

 margin of the leaf of this grass is armed with minute sharp transparent 

 teeth inclined toward the apex. 



Makahna is less than 1,000 feet high. At its summit we saw the 

 remains of a signal station. We had a magnificent view. The city of 

 Agaiia was concealed beneath the edge of the cliffs, but a great part of the 

 island appeared to us as though spread out on a map. Dr. Mayer pointed 

 out to me the effects of denudation on the slopes of the volcanic peaks to 

 the southward. Although the products about us were plainly volcanic, 

 it appears that much of the red soil elsewhere which I had regarded as vol- 

 canic in origin is simply disintegrated limestone colored by iron oxide. 

 Where this has been washed down into valleys and become mixed with 

 organic matter it forms a stiff, black, adobe-like soil. 



During our excursion Dr. Mayer's assistant, a sailor from the Alba- 

 tross, had been busy collecting insects, blue-tailed, bronze-striped lizards, 

 land-shells, and other things. He seemed to enjoy his work thoroughly. 

 The butterflies were of small size as a rule. Some of the dragon flies 

 were bright scarlet. Dr. Mayer told me of some interesting work in which 

 he had been engaged — investigating the sense organs of lepidoptera. He 

 has also studied the phenomena of color in the wings of moths and 

 butterflies ; not only the origin and nature and development of the color 

 itself in the individual, from its larval to the full-grown stage, but also the 

 laws of variation in allied species and varieties, and the phenomena of 

 mimicry in those forms which imitate the colors and color-patterns of 

 others of distinct species. His observations prove, among other things, 

 that the scales of lepidoptera do not strengthen the wings or aid the 

 insects in flight, but are for the most part merely color-bearing organs 

 developed under the influence of natural selection.* During the present 

 cruise he has been interested in the study of jelly-fish and other marine 



*Dr. Maj'er is now Curator of the Museum of the Brooklyn Instilutue of Arts and Sciences. For 

 his observations " On the Color and Color-patterns of Moths and Butterflies," see Bull. Mus. Compara- 

 tive Zoology at Harvard College, No. 30, p. 169 ; 1897. 



