174 UNIVERSITY OF COLORADO STUDIES 



sways the audience to his own mood. Surely no one will argue that 

 light makes the whole nervous mechanism, which at last responds to 

 the eye, thus become an active guide of locomotion. This would be 

 to attribute to matter a creative power sui generis that would be more 

 spiritual and mysterious than teleology. 



But, does someone object, there are facts, well known facts to 

 prove that outer stimuli do cause enormous changes : what about the 

 species whose very natures are changed by salt solutions ? Well, this 

 seems at first sight to be plausible. But does the salt solution cause 

 the change ? What is a cause ? There is a real impelling cause as 

 when a cue hits and moves a billiard ball; there is a releasing cause 

 as when a spark ignites a carload of gunpowder; and then there is an 

 unwinding cause as in the spring of a victrola. Are the two latter 

 very real causes ? No. But the salt solution is just midway between 

 these. It is an occasion of variation rather than a real cause. 



As applied then to the explanation of the development of the eye, 

 Eimer's view is pure finalism. The production of an eye in two widely 

 different species by two entirely different series of infinitely numerous 

 small causes is contrary to the principles of mechanism. 



Up to this point, we have talked of the eye of a species, but study 

 of the eye in an individual of a species shows the same reasoning is 

 sound. If a lens is removed, it may be regenerated in the greatest 

 variety of ways. 



The result so far is that the pretended mechanism, or accident of 

 natural necessity, is a mere pretense in these three systems, and every 

 one of them has some inner directing agent, which it alternately denies 

 and makes use of. The convergence of effects in lines of life so remote, 

 the eye appearing in species so disconnected, and of so various experi- 

 ence, can never be explained by mechanics. 



Now what about neo-Lamarckism ? Lamarck explained variation 

 by use or disuse of organs, that is, practice and effort, and by trans- 

 mission of characters thus acquired to descendants. His disciples 

 attribute such variations not to mere mechanism, but to effort, some- 

 times voluntary effort, at adaptation to environment. This effort 

 may be only the mechanical exercise of organs under pressure of cir- 



