May 2 2, 1890] 



NA TURE 



85 



FRIENDLY ISLANDS 



Scale of Sa« M.let 



Can we, however, carry the argument one stage 

 further? Why should the seed of the sycamore be 

 globular, and that of the beech triangular? Is it clear 

 that the cotyledons are constituted so as to suit the seed ? 

 May it not be that it is the seed which is adapted to the 

 cotyledons? In answer to this we must examine the 

 fruit, and we shall find that in both cases the cavity of 

 the fruit is approximately spherical. That of the syca- 

 more, however, is comparatively small, say \ inch in 

 diameter, and contains one 

 seed, which exactly conforms 

 to the cavity in which it lies. 

 In the beech, on the contrary, 

 the fruit is at least twice the 

 size, and contains from two 

 to four fruits, which conse- 

 quently, in order to occupy 

 the space, are compelled (to 

 give a familiar illustration, 

 like the segments of an 

 orange) to take a more or 

 less triangular form. 



Thus, then, in these cases, 

 starting with the form of the 

 fruit, we see that it governs 

 that of the seed, and that of 

 the seed, again, determines 

 that of the cotyledons; But 

 though the cotyledons often 

 follow the form of the seed, 

 this is not invariably the 

 case : other factors must 

 also be taken into considera- 

 tion ; but when this is done, 

 we can, I venture to think, 

 throw much light on the 

 varied forms which seedlings 

 assume. 



I have thus attempted to 

 indicate some of the prin- 

 <:iples on which, as it seems 

 to me, the shapes of leaves 

 and seedlings depend, and to 

 apply them in certain cases, 

 but the study is only in its 

 infancy : the number and 

 variety of leaves is almost 

 infinite, and the whole ques- 

 tion offers, I venture to think", 

 a very interesting field for 

 observation and research — 

 one, indeed, of the most 

 fascinating in the whole of 

 natural history. 



EUA ISLAND, TONGA IJEI^ 



GROUP. 

 'X'HE following description 

 -■■ of Eua Island (one of 

 the higher members of the 

 Friendly or Tonga Islands, 

 and familiar to readers of 

 ** Cook's Voyages" as Mid- 



dleburgh), written by Commander Oldham, of H.M. sur- 

 veymg-ship Egeria, will be of interest to geologists and 

 those interested in the coral controversy. 



W. J. L. Wharton. 



" When viewed from the westward, Eua is seen to con- 

 sist of grassy table-lands and slopes, having clumps of 

 dark-green trees dotted here and there, giving it a park- 

 like appearance. It is formed of two coral terraces rest- 



ing on a volcanic nucleus. The upper terrace, about 600 

 feet above the level of the sea, rises to a summit 1030 feet 

 high ; the lower terrace attains a height of only 350 feet. 

 On the western side of the island these terraces are 

 separated a distance of from one to one and a half miles, 

 and in some places there is a depression between them ; 

 the eastern side is very precipitous, the terraces there 

 being very narrow, and forming cliffs at their seaward 

 edges. 



NO. 1073, VOL. 42] 



" The upper terrace seems composed of foraminiferous 

 limestone and reef rock, with volcanic rock (a hydrated 

 oxide of manganese) cropping out on the western side at 

 the edge of the terrace where the coral rock has been 

 removed by the effects of weather. The limestone is 

 compact, reddish-brown, and largely foraminiferous. It 

 is both in situ and scattered in detached blocks over the 

 upper terrace, and when weathered has a honeycombed 

 appearance. 



