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proximations to the cube than is consistent with their primitive form. 

 That thi6 alteration of the angle is due to the action of heat, and that 

 the degree of heat is indicated by the angle ultimately assumed, is 

 evident from the following remark by Prof. Brande : — " The tempera- 

 ture appears to affect the mutual inclinations of the planes of crystals. 

 In the case of carbonate of lime, it amounts, according to Mitscher- 

 lich, to as much as 8.5' in the interval of temperature between 32° 

 and 112.° As the temperature augments, the smaller axis of the 

 rhomboid dilates more than its other diagonals, so as to cause an ap- 

 proach to the cubical form." 



It is my chief object, however, to show, with Ehrenberg, that ani- 

 mals of the chalk are still found in a living state ; and having done 

 this, it is needless, with Ehrenberg's paper in our hands, to point out, 

 at any length, the importance of these researches. They bear directly 

 upon mountain masses, and seem to make the vast chalk-range over- 

 step its boundary, and connect itself rather with the tertiary and re- 

 cent, than with the primary and transition formations. Beyond all 

 doubt the bulk of the cretaceous series is composed of organisms still 

 living, as I have now shown, in our own British seas, and, as Ehren- 

 berg observes, still capable, under the concurrence of favourable cir- 

 cumstances, of giving rise to the greatest changes in the distribution 

 of the solid crust of the earth. The material, and not the magnitude 

 of Infusoria is the proper element in these calculations. We must 

 shut our eyes to the minuteness of each individual atom of life, and 

 look rather at the marvellous activity of its law of increase, and at its 

 indestructible shield, which sets at defiance the two great reducers of 

 organic structure, death and fire. A very few nut-shells would hold 

 all we should leave of an elephant if reduced to its ultimate elements 

 by fire, but no known intensity of heat would reduce the siliceous 

 mass of Infusoria. Fusion, under certain conditions, would be the 

 utmost result, and thence would originate other mountain masses, 

 which, to say the least, would be very nearly allied to those which 

 we term granitic. The question, then, is not unreasonable — was 

 granite originally an infusorial earth ? — and we accept Ehrenberg's 

 hypothesis as the reply : "Since of the four as yet well established 

 great geological periods of the earth's formation, the quaternary, 

 tertiary and secondary formations contain recent organisms, it is as 

 three to one more probable that the transition or primary formation 

 is not differently circumstanced, but that, from the gradual longer 

 decomposition and change of many of its organic relations, it is more 

 difficult to examine and determine." 



