20 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



structure in animal forms, and by the physiologist who, 

 studying the body in its aspect as a mechanism 

 for liberating the locked energy of chemical mole- 

 cules in forms of material, and perhaps of mental, 

 life finds an extravagance of material and a riot of 

 design that baffles his description almost as much 

 as his comprehension. But he always remembers 

 that his question is not why, but how. When 

 Helmholtz, after his investigation of the optics of 

 the human eye-ball, drew attention to the mani- 

 fold optical defects in that structure, and wrote that 

 an optician would discharge a workman for producing 

 so optically imperfect an instrument, it appeared to some 

 that such a criticism was impious in character. The 

 attribution of impiety to such expression shews how liable 

 to confusion are the two lines of enquiry of the why and 

 how. As Helmholtz himself points out in the most 

 beautiful of passages, so inconceivably admirable is the 

 wonderful mechanism of the nerves and brain upon which 

 the optic parts of the eye-ball throw their relatively 

 imperfect pictures of the visible world, that despite these 

 defects, the sense of vision results, with all its marvels, 

 and builds the chiefest basis and scaffold for the uprearing 

 of the indescribable edifice of the human mind. 



