GENEOLOGICAL. 419 



of digits ; and there are other possible explanations. 



About a hundred years ago (1796), an authority 

 on trotting horses stated that the utmost speed of the 

 English trotter was a mile in 2 minutes, 57 seconds^ 

 Since 1818, accurate trotting records have been kept, 

 and an inspection of these shows that very gradu- 

 ally, decade after decade, the speed and the percent- 

 age of swift trotters increased. Finally there has 

 been evolved a breed who can trot the mile in 2 

 minutes, 10 seconds. It is claimed by Cope and 

 others that we have here evidence of the cumulative 

 transmission of the results of exercise or nurture. 

 But a sceptical consideration leads one to doubt if 

 the case is even relevant ; the interpretation in terms 

 of use-inheritance overlooks the results of selective 

 breeding which may have increased the congenital 

 swiftness, and the process of elimination which per- 

 sistently weeded out the less swift from the stud. 



Reference is often made in biological literature 

 to the observations and experiments of Schmanke- 

 witsch in 1875 on certain brine-shrimps belonging to 

 the genus Artemia. By lessening the salinity of 

 the water he was able to transform one type, Ar- 

 temia salina, in the course of generations into an- 

 other type, Artemia milhausenii; and conversely, by 

 increasing the salinity. Although he did not him- 

 self make any such claim, his work has often been 

 referred to as an illustration of changing one species 

 into another. It had indeed the undeniable result 

 of showing that certain forms of life are very plastic, 

 even to such influences as altered salinity. Apart 

 altogether from the criticism of experts, which has 

 been damaging, it may be recognised that Schmanke- 

 witsch experimented w^ith a progressively changing 

 environment on a series of generations, and that the 



