334 Ml*. Sorby on the Microscopical Structure of Meteorites. [June 16, 



(L'Aigle). This sometimes gives vise to a structure remarkably like that of 

 coiisohdated volcanic ashes, so much, indeed, that I have specimens which, 

 at first sight, might readily be mistaken for sections of meteorites. It would 

 therefore appear that, after the material of the meteorites was melted, a 

 considerable portion was broken up into small fragments, subsequently col- 

 lected together, and more or less consolidated by mechanical and chemical 

 actions, amongst which must be classed a segregation of iron, either in the 

 metallic state or in combination with other substances. Apparently this 

 breaking up occurred in some cases w^hen the melted matter had become 

 crystalline, but in others the forms of the particles lead me to conclude 

 that it was broken up into detached globules whilst still melted (Mezo- 

 Madaras, Parnallee). This seems to have been the origin of some of the 

 round grains met with in meteorites ; for they occasionally still contain a 

 considerable amount of glass, and the crystals which have been formed in 

 it are arranged in groups, radiating from one or more points on the external 

 surface, in such a manner as to indicate that they were developed after the 

 fragments had acquired their present spheroidal shape (Aussun, &c.). In 

 this they differ most characteristically from the general type of concretionary 

 globules found in terrestrial rocks, in which they radiate from the centre ; 

 the only case that I know at all analogous being that of certain oolitic 

 grains in the Kelloways rock at Scarborough, which have undergone a 

 secondary crystallization. These facts are all quite independent of the 

 fused black crust. 



Some of the minerals in meteorites, usually considered to be the same as 

 those in volcanic rocks, have yet very characteristic differences in structure 

 (Stannern), which I shall describe at greater length on a future occasion. 

 I will then also give a full account of the microscopical structure of meteoric 

 iron as compared with that produced by various artificial processes, shoAnng 

 that under certain conditions the latter may be obtained so as to resemble 

 very closely some varieties of meteoric origin (Newstead, &c.). 



There are thus certain peculiarities in physical structure which connect 

 meteorites with volcanic rocks, and at the same time others in which they 

 differ most characteristically, — facts which I think must be borne in mind, 

 not only in forming a conclusion as to the origin of meteorites, but also in 

 attempting to explain volcanic action in general. The discussion of such 

 questions, however, should, I tbink, be deferred until a more complete 

 account can be given of all the data on which these conclusions are founded. 



XIII. "On the Functions of the Cerebellum.^' By W. H. Dickin- 

 son, M.D. Communicated by Dr. Bence Jones. Received 

 June 16, 1864. 



This is a revised version of a Paper having the same title which was read 

 on the 7th of April, 1864, and of which an Abstract appeared under that 

 date *. 



* See p. 177, 



