"The final step would be a thorough anatomical study of the species found in the cave, with extensive com- 

 parison of allied species, found elsewhere; next, an investigation of the embryology of all of them, and when 

 fully prepared by such researches, an attempt to raise embryos of the species found in the cave, under various 

 circumstances, different from those in which they are usually found at present. 



"If physical circumstances ever modified organized beings, it should be easily ascertained here. For my own 

 part, however, I think that the blind animals of the cave would only show organs of vision during their embry- 

 onic state in conformity with the normal development of the respective types to which they belong, that even 

 when placed under a moderate influence of light, incapable of injuring them, but sufficient to favor the growth 

 of their eyes in the allied species provided with them, the young of those species peculiar to the cave would grad- 

 ually grow blind, while the others would acquire perfect eyes; for I am convinced, from all I know of the geo- 

 graphical distribution of animals, that they were created under the circumstances in which they now live, within 

 the limits over which they range, and with the structural peculiarities which characterize them at the present day. 

 But this is a mere inference, and whoever would settle the question by direct experiment might be sure to earn 

 the everlasting gratitude of men of science. And here is a great aim for the young American naturalist who would 

 not shrink from the idea of devoting his life to the solution of one great question." — Agassiz. 



