496 THE AMERICAN NATURALIST. [Vol. XXXVIII. 



will differ from the method prev^ailing in the original home, 

 though under certain circumstances it may have been tried by 

 some of the original stock. New relations having been estab- 

 lished with the environment, and the swamping effect of associa- 

 tion and intergeneration being removed, divergent evolution is 

 insured. Two genera of the Achatinellidae are found almost 

 exclusively on the ground among the dead leaves. The diver- 

 gence between these genera living on the ground and those liv- 

 ing on the trees and shrubs was probably gradually introduced 

 in some such way. In the same way may have arisen the differ- 

 ences between the genus of minute species feeding on the leaves 

 and the genera of larger forms feeding on what is found on the 

 trunks and branches of the trees. 



The Function of the Lateral Line Organs in Fishes: G. H. 

 Parker, Harvard University. — This work was carried on at the 

 Biological Laboratory of the United States Bureau of Fisheries 

 at Woods Hole, Massachusetts. Tests were made on smooth 

 dogfish, skates, winter flounders, scup, and two species of Fun- 

 dulus. The action of the lateral line organs was eliminated by 

 cutting the branches of the fifth, seventh, and tenth nerves sup- 

 plied to these organs. After recovery from shock the reactions 

 of individuals on which these operations had been carried out 

 were compared with those of normal fishes. No significant dif- 

 ferences could be discovered in the' reactions of normal and oper- 

 ated fishes to the following stimuli : temperature changes from 

 9^ C. to 30° C. ; salinity changes having a range between a mix- 

 ture of one part sea water and four parts fresh water, and sea 

 water concentrated to three fourths its original volume ; reduced 

 oxygen supply ; increased carbon dioxide ; foul water : reduction 

 of pressure to nine pounds ; increase of pressure to twenty-two 

 pounds ; and currents of water. On testing for equilibrium it 

 was found that the lateral Ime organs were of no more signifi- 

 cance in this respect than the general integument. Normal and 

 operated fishes did not respond differently to sound vibration of 

 " 100 per second. Operated fishes failed to respond 



•ibration 



per second, whereas normal 



fishes reacted to these with great precision. The lateral 



