256 THE PRESENT IMPORTANCE OF SCIENCE 



mental questions involved, the federal government has con- 

 structed, at Fairport, Iowa, a station for the investigation of 

 these and all other problems of fresh-water biology, and as a 

 part of this station, a hatchery for the rearing of mussels by 

 artificial means. 9 



Although much remains to be done before the rearing of 

 the button mussels is established upon a commercial basis, 

 the results are encouraging and it may be hoped that before 

 many years the supply of raw material will be drawn from 

 beds artificially produced and maintained. As this work in 

 applied science advances, it is conceivable that the men who 

 have dealt with these practical problems may win popular 

 recognition greater than that given to any of their pred- 

 ecessors during the two hundred and fifty years since 

 Leeuwenhoek. Be this as it may, it is to the earlier workers 

 that the larger measure of credit belongs; for theirs was the 

 more unique attainment. Between the two is the difference 

 between the men who broaden a beaten trail and those who 

 penetrate territory wholly new. 



THE PROGRESS OF KNOWLEDGE CONCERNING HEREDITY 



The problem of heredity is our final illustration of the 

 relation between theoretical and practical knowledge in the 

 history of science. In this field we have known so little, 

 have so failed in the discovery of land-marks until very recent 

 years, that biological science is only beginning to get its 

 bearings and to hew its way into the wild. We to-day stand 



cial Propagation of Fresh-water Mussels." Bulletin Bureau of Fisheries, 

 Vol. XXX, 1910. See also: the miscellaneous papers by other investigators, 

 published in Bull. Bur. Fisheries since 1910; and particularly, Coker, R. E. 

 et al. " Natural History and Propagation of Fresh-water Mussels," Bull. 

 Bur. Fisheries, Vol. XXXVII, 1919-20. 



9 This station, which is probably the most extensive establishment of its 

 kind in the world, is described briefly by R. S. Coker, "The Fisheries Biological 

 Station at Fairport, Iowa." App. I, Rept. U. S. Commissioner of Fisheries, 

 1920. 



