'Notes and Comments. 211 



the South Eastern Union can be congratulated on ' carrying 

 on ' so well ; in this respect the child setting a good example 

 to the elderly, but we hope not less energetic parent — the York- 

 shire Naturalists' Union ! 



SCIENCE PROGRESS. 



The interesting nature of the contents of this Quarterly, 

 edited, and to a large extent written, by Sir Ronald Ross, 

 causes us eagerly to await its appearance. No. 44 contains 

 a variety of contributions, including ' Polymorphism,' by 

 F. D. Chattaway, F.R.S. ; ' Osmotic Pressure in Animals and 

 Plants,' by W. R. G. Atkins, Sc.D., and ' The History of 

 Comparative Anatomy, Part I. ; a Statistical Analysis of the 

 Literature,' by F. J. Cole, D.Sc, and N. B. Eales. There are 

 also useful summaries of the recent advance in different 

 branches of science, by specialists. 



AGE OF THE EARTH. 



' Salt and the Age of the Earth,' by G. W. Bulman, deals 

 with Prof. Joly's estimate of the age of the earth by estimating 

 the quantity of salt annually washed into the sea, where it ac- 

 cumulates. Assuming an original saltless ocean, and dividing 

 the amount of salt in the ocean by the amount carried down 

 each year, the age of the earth is estimated to be something 

 like ninety million years. ' Now, if we compare in a broad 

 and general way these salt deposits from the Silurian to the 

 Miocene, it is impossible to suggest that Tertiary oceans were 

 Salter than the Primary, as they ought to have been. The 

 sea which could give us the salt beds of the Salina group of 

 North America, and those of the Indian salt range, must have 

 contained — one suggests — at least as much salt as those of 

 to-day, or of the Miocene which gave the Polish deposits. Nor 

 can we think that our Triassic salt deposits, or the German 

 Permian, came from oceans richer in salt than these Devonian 

 seas which yielded the salt of the salt range.' 



SALT WATER AND SALMON. 



' And if, as Prof. Joly suggests, the rocks of the earth 

 are having their sodium contents washed out continually, 

 the newer formed deposits should have less than the older. 

 Thus, a river which is cutting its way through Triassic rock 

 may be dealing with matter which has had its sodium subject 

 to a like action, say in Carboniferous times. The rivers of 

 to-day must be bringing down less sodium than those of the past. 

 Is this possibly why the salmon requires to go to the sea ? 

 The river having become too fresh for it, the salmon must go 

 for the necessary saltness to the ocean. The eel, also, may 

 have found it impossible to complete its life history in the 

 river's growing scarcity of salt. 



1917 July 1. 



