1888.] NATURAL SCIENCES OF PHILADELPHIA, 265 



Of 90 examples I found the left sutural ruga thus deflected in 49 

 instances, the right, in 3 instances only, and on both right and left, 

 5 instances. In all the other examples the fold was transverse. In 

 deflection it must be noted that the ruga after reaching the raphe 

 is thence abruptly turned so as to be parallel v/ith that structure. 

 Both the right and the left fold may be inclined back before ap- 

 proaching the raphe or may not reach it at all. 



The forms of the rugse are never pathological as I venture to 

 define that term. The question to what extent variations of struct- 

 ure may be said to be pathological is no longer a novel one. The 

 fact that the forces operating in the economy often antagonize is 

 generally accepted. Upon this antagonism the approach to sym- 

 metry as seen in the paired structures alone depends. In the 

 plastron of a turtle ( Chrysemys pida) in my possession, the plates 

 exhibit a constant disposition for those of the right side to crowd 

 and minimize those of the left. The same disposition for one side to 

 gain ascendency is seen in all paired structures which form by their 

 growth inward a median suture or raphe. If such minor variations 

 were to be called pathological every living creature would be an 

 epitome of morbid anatomy. Anatomical variation I assume to be 

 a better term for such deviations unless the structures are hurtful to 

 the individual or at least tend to be so. A pathological condition 

 is one in which the final effect is to create distress or to excite 

 lesion. Prof Alpheus Hyatt has described certain distorted shells 

 found by him as constituting pathological species. Are not such 

 species degraded, or reverted rather than pathological forms? The 

 comparison sometimes made between the horn of the rhinoceros 

 and the epidermic hypertrophies which appear upon the surface of 

 n;ian and some of the lower animals, is based upon the conception 

 that the outgrowths are in both instances of the same nature, — that 

 they are both pathological and differ only in the single feature that 

 the rhinoceros by the law of selection has utilized a horn which 

 happened to appear at a convenient locality. To my mind the 

 structure is not pathological unless it expresses perverted function 

 or interferes with a function ; not only this but that it interferes in 

 an abrupt, obstructive manner. If it does not so appear but in 

 such guise as to encourage the animal to use it; the organ should 

 be named an anatomical variation. 



The word pathology is an anachronism in a system of biology. 

 It originated at the hands of observers who had imperfect concep- 



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