Appendix 363 



spiral. Roll the curve along an indefinite 

 straight line. Its pole will become displaced 

 while still keeping on one straight line. The 

 endless scroll leads to rectihnear progression ; 

 the perpetually varied begets uniformity. 



Now is this logarithmic spiral, with its curious 

 properties, merely a conception of the geometers, 

 combining number and extent, at will, so as to 

 imagine a tenebrous abyss wherein to practise 

 their analytical methods afterwards ? Is it 

 a mere dream in the night of the intricate, an 

 abstract riddle flung out for our understanding 

 to browse upon ? 



No, it is a reality in the service of life, a 

 method of construction frequently employed in 

 animal architecture. The Mollusc, in particu- 

 lar, never rolls the winding ramp of the shell 

 without reference to the scientific curve. The 

 first-born of the species knew it and put it into 

 practice ; it was as perfect in the dawn of crea- 

 tion as it can be to-day. 



Let us study, in this connection, the Ammon- 

 ites, those venerable rehcs of what was once 

 the highest expression of living things, at the 

 time when the sohd land was taking shape from 



