454 



Da nobis panem, Domine f in diebus nostris ; non durum et la- 

 pideum, sed frugalem ac sufficientem. 



I should not have thus introduced, in our examination of the 

 petrification of vegetable matter, the mention of petrified loaves, 

 but for the sake of observing, that, of all the sports of nature, in 

 the formation of stones, these are among the most delusive, and 

 unaccountable; judging from a specimen in my possession, which 

 I understand was obtained by the late Mr. Strange, from Germany, 

 at considerable trouble and expense. Its form is that of a long 

 square, being similar to what are generally called Dutch loaves. Its 

 upper surface is rounded, and of a dark brown, exactly agreeing in 

 shape and colour to the upper crust of such a loaf; whilst its oppo- 

 site surface is flattened, and of a paler brown; bearing as perfect an 

 agreement with the under crust : both the one and the other pos- 

 sessing the smooth surface of the crust of a loaf. The intermediate 

 substance, answerable to the crumb, possesses, in an extraordinary 

 manner, the rough spongy appearance of the crumb of bread, be- 

 ing even separated by such clefts as might be supposed to have 

 taken place in bread which had been dried by long keeping. The 

 substance of the stone appears to the naked eye like a coarse jas- 

 per ; but on a close examination, with the aid of a glass, the inter- 

 nal substance is discovered to be formed of very small white sili- 

 cious stones, agglutinated by a silicious medium ; and the external 

 part of brown silicious stones, connected in a similar manner : the 

 substance of our seeming petrified loaf turning out to be actually a 

 plum-pudding stone formed in some cavity, most probably left by 

 the decomposition of some substance ; ,but what this substance had 

 been it seems impossible to ascertain. The late truly respectable 

 Dr. Gray, of the British Museum, thought it not improbable that 

 this stone had formed part of the nucleus of an immensely large 

 solen. 



The substances represented at Plate IX. Fig. 8 and 9, have ob- 



