INVESTIGATING OKGANIC FORMS. 209 



be taken. Was it not possible, by ascertaining the accurate 

 shape, the form and proportion between the parts, organs, and 

 whole body of any animal, to advance the study geometrically? 

 Suppose the anatomist gave the exact curvature of the surface, 

 the volume and proportions which different parts of the organs 

 might bear what their formal geometry was might become 

 matter of calculation. He might begin, by the lengths, and 

 breadths, and volumes of the different parts, by ascertaining 

 whether they have a correspondency, and exhibit a mathema- 

 tical relation, spherical or spheroidal curves, etc. These once 

 ascertained, he would become certain of the geometrical con- 

 struction, and could reason as to the probable forms of other 

 parts. 



Impossible as it might appear, this had been effected in 

 Certain instances, and especially in a most beautiful manner 

 in regard to shells of molluscous animals, by the Eeverend 

 Professor Moseley, late of Cambridge,* who had made an exact 

 geometrical examination of shells, and especially of the Tur- 

 bines, which were possessed of a spiral curve wound round a 

 central axis, which curve had been found to be logarithmic, and 

 from it had been framed a series of formulae, by which the other 

 conditions of the shell could be predicted and found to exist. 



By a very accurate measurement of the shell, mathemati- 

 cally, it was found that its spires increased in breadth in an 

 exact successive series, each one of which was a multiple, in 

 a certain ratio, of another. Thus there was a mathematical 

 principle arrived at, which could be carried out the shell 

 must possess this form, and could possess no other. It had 

 a spiral curve, and the properties of that curve pointed it 

 out to be a logarithmic curve, one which would reproduce 

 itself; a curve formed by a thread wound off the exterior, 

 would trace the form of its operculum ; and the mouth of 

 the animal was remarkable for geometrical symmetry. As 



* Philosophical Transactions, 1838, p. 351. 

 P 



