446 



POPULAR SCIENCE MONTHLY. 



ers as a fluviatile species. This genus, 

 Io, varies greatly in different parts of 

 the Tennessee basin. In some places it 

 is smooth; in others, spiny; in others, 

 long drawn out. Under a grant of the 

 Association, Mr. C. C. Adams, of Bloorn- 

 ington, 111., visited this region; trav- 

 elled down one of the tributaries in a 

 boat, collecting samples from every 

 community of Ios ; and went by train up 

 a second river collecting at every stop- 

 ping place. The results of this trip 

 were, in a word, that in passing from the 

 mouth to the headwaters of the two 

 parallel tributaries the shells vary in 

 parallel fashion and show a uniform, 

 continuous change from the spiny, elon- 

 gated condition characteristic of the 

 mouths of the rivers to the smooth, 

 more globose condition characteristic of 

 the headwaters. The additional grant 

 by the Association of one hundred dol- 

 lars will assist Mr. Adams in making 

 further quantitative studies on varia- 

 tion in the genus Io. 



Hardly any fact has excited more 

 interest among evolutionists than the 

 blindness of cave animals; and various 

 theories have been advanced to explain 

 the fact. It is known that the blind 

 condition is due to a degeneration of 

 formerly fuctional eyes. The difficulty 

 has been to understand what ad- 

 vantage is gained by losing the 

 eyes even in a locality where eyes 

 are of no use. It has been affirmed that 

 'Nature is economical' and will not ex- 

 pend energy in building an unnecessary 

 organ. Weismann has suggested that 

 the only reason why we have eyes at all 

 is because Natural Selection is constant- 

 ly weeding out poor eyes. Withdraw 

 the necessity for good eyes, and poor 

 eyes and good eyes will have an equal 

 chance of surviving. According to a 

 third theory, the functional activity of 

 any organ is essential to its mainten- 

 ance. Just as the unused arm withers 

 so the unused eye degenerates. Of 

 course all these theories assume that 

 the ancestors of the blind species — for 

 instance, of the blind fishes — had orig- 



inally no inherent tendency to blind- 

 ness or degeneration of the eyes. This 

 assumption has, however, be«n recently 

 combatted by Professor Eigenmann, 

 who has shown that although many 

 kinds of fish are accidentally swept into 

 caves, only one kind has become blind: 

 of this kind the nearest allies which 

 live in open streams shun the light, 

 live in crevices and under stones, and 

 have less perfect eyes than other fishes. 

 Some of the allies of such light-shun- 

 ning fishes have made their way into 

 caves, and have there worked out their 

 tendency to a reduction of eyes. That 

 has been the history of eyeless fishes. 

 To continue the researches of Professor 

 Eigenmann, so auspiciously begun, the 

 Association last year granted one hun- 

 dred dollars to a committee on the cave 

 vertebrates of North America. With 

 the aid of the grant Dr. Eigenmann has 

 during the past year penetrated into 

 numerous caves and obtained much 

 additional material for his researches. 



The American Association will meet 

 next year at Denver, beginning on Au- 

 gust 26th. The newly elected officers 

 are: 



President. 



Prof. Charles Sedgwick Minot, Har- 

 vard Medical School. 



Vice-Presidents. 



Mathematics and Astronomy: Prof. 

 James McMahon, Cornell University. 



Physics: Prof. D. D. Brace, Univer- 

 sity of Nebraska. 



Chemistry: Prof. John H. Long, 

 Northwestern University. 



Mechanical Science and Engineering: 

 Prof. H. S. Jacoby, Cornell University. 



Geology and Geography: Prof. C. 

 R. Van Hise, University of Wisconsin. 



Zoology: President D. S. Jordan, 

 Leland Stanford Jr. University. 



Botany: B. T. Galloway, U. S. De- 

 partment of Agriculture, Washington, 

 D. C. 



Anthropology: J. W. Fewkes, Bu- 

 reau of Ethnology, Washington, D. C. 



Economic Science and Statistics; 



