98 Geological Society. 



and the purpose which they answer in the animal economy. He had 

 discovered in the lenses of many fishes the alternation of portions, 

 exerting:, the one a positive, and the other a negative refractive 

 action ; but in his subsequent investigations he met with the greatest 

 discrepancy as to the regularity of their arrangement. He found 

 that in quadrupeds the central structure is positive j while in fishes, 

 where there are three structures, it is always negative ; but their po- 

 sitive structure in the former case sometimes exists alone, with faint 

 traces of a negative structure, and sometimes it is followed by 

 another positive structure separated from the first by a black neutral 

 circle, in which the double refraction disappears ; at other times va- 

 rious other combinations of these structures are presented, Occa- 

 sionally, in the dark neutral line which separated two positive struc- 

 tures, he perceived a trace of an intervening structure, which seemed 

 to be either about to disappear or about to be developed. This con- 

 jecture was satisfactorily verified by a series of observations which he 

 made on the lenses of the sheep, the ox, and the horse, at different 

 ages, and also on the same lens, during the spontaneous changes 

 it undergoes when kept in distilled water. The negative structure 

 was in these experiments gradually developed at the space inter- 

 vening between the portions of the lens which had possessed the 

 positive structure ; and thus the same parts assumed in succession 

 doubly refractive actions of opposite kinds. The author intimates 

 his intention of pointing out, in a separate paper, the conclusions 

 deducible from these facts respecting the cause and cure of cataract. 



GEOLOGICAL SOCIETY. 



January4. — A paper entitled, " Some Observations on the Elevation 

 of the Strata on the Coast of Chili," by Alexander Caldcleugh, Esq., 

 F.G.S., &c, was first read. 



The author commences by stating, that previously to his return to 

 South America several circumstances induced him to suspend 

 his opinion as to the correctness of the details which had been 

 published of the effects of the earthquake of 1822. He thought that 

 the wreck in the Bay of Valparaiso, which had become accessible after 

 the earthquake, might have been thrown higher up by the heavy rollers, 

 and that rocks covered with testacea, which after the event were laid 

 dry, might likewise have been drifted. He also thought that the ac- 

 curacy of the observations might be doubted, because certain genera 

 of shells were stated to have been found adhering to the rocks in 

 Valparaiso Bay, which it was well known did not exist there ; and 

 because there was a vagueness in some of the statements, — as the 

 raising of the whole country from the foot of the Andes to far out at 

 sea. Since his return to South America, however, especially since 

 the earthquake of 1835, Mr. Caldcleugh has investigated the evi- 

 dences of change of level on the Chilian coast, and he states, in this 

 communication, his full conviction, that there have been many distinct 

 alterations in the relative level of land and sea. 



