W. B. DWIGrHT. 133-(103) 



opposite sides of the head, as in most animals. But as 

 maturity advances, one of these eyes abandons its moor- 

 ings, forces its way up through the liesh and skin to the 

 other and upper side, taking its place, though in a curi- 

 ously oblique position, by the side of the other eye. — 

 The embryonic position is here exceptionally the higher 

 one. The mature position is one very useful and appro- 

 priate to the habits of the animal, but a deformity in 

 symmetry, and a degradation in rank.'- 



These exceptions, however, should not impair our 

 faith in the law. They simply arise from the counter- 

 working, in these cases, of another w T ell-established law. 

 In accordance with this latter law, certain embryonic or- 

 ganisms up to a certain stage develop some organs which 

 are the rudimentary beginning of a higher grade of life 

 than that to which in maturity they are destined to be- 

 long ; but there comes a point in the progress when these 

 organisms cease to develop those organs any further. 

 Such animals are specialized in some direction, to which 

 these organs are not fitted, and the latter are consequently 

 suppressed or subordinated to other organs adapted to 

 the low grade of the creature's life. In all these cases 

 such organs are suppressed, not because they are too low, 

 but as in the case of the teeth of the whalebone whales, 

 because they are too high in type for the mature habits 

 of the animal. 



The second great law was enunciated by Professor J. 

 D. Dana, and was at once accepted by scientists under 

 the name of the law of cephalization. This principle 

 assumes that in proportion as the anterior parts of a 

 body are compacted, or as the number of organs contri- 

 buting to the functions of the head extremity is large, 

 the rank is so far high. But in proportion as the num- 

 ber of separate segments in the hinder parts of the body 

 is large, or the body is posteriorly prolonged, the grade 

 is by so much inferior. In short, condensation head- 

 wards is a sign of superiority ; expansion posteriorly is 

 a sign of inferiority. 



In the interpretation of this law, the arrangement of 

 the nervous system is the important consideration, as it 

 is the key to the type of any animal structure. Cephali- 



*This point, however, will apparently not be granted by those zoologists, who on the 

 gr<?u»<i of higher speqializatiou. assign the flat-fishes the highest rauk Ln their arvjer. 



