THE PHENOMENA OF MUTATION 181 



descended from these commercial seeds, but the 

 Swedish race of Lamar ckiana, as well as those of 

 English gardens, differ in several features and must 

 have come from another source or been modified 

 by crossing with grandiflora. This last remark is 

 quoted from Gates, but it seems improbable that 

 the Dutch plants should be derived from those of 

 Lancashire, and those of English gardens from a 

 different source. The fact seems to be, according to 

 other parts of Gates's volume, that there arc vaiious 

 races of Lamarckiana in English gardens and in the 

 Isle of Wight, as well as in Sweden, etc., and that 

 these races diifer from one another less than the 

 mutants of De Vries and his followers. 



An important point about these mutations is that 

 their production is a constant feature of Lamarck la )iu. 

 Whenever large numbers of the seeds of this plant are 

 grown, a certain proportion of the plants developed 

 present these same mutations ; not always all of 

 them — some may be absent in one culture, present 

 in another, but four of them are fairly common and 

 of constant occurrence. The total proportion of 

 mutant plants compared with the normal was 1*55 

 per cent, in one family, 5*8 per cent, in another. It 

 would appear therefore, supposing that mutations 

 arose subsequently in the same determinate way 

 from previous mutations, that evolutioii, though in 

 a number of divergent directions from one ancestral 

 form, would proceed along definite lines, and that 

 there would be nothing accidental about it. We 

 should thus arrive at a demonstration of what 

 Eimer called orthogenesis, or evolution in definite 

 directions. 



The mutation lata cannot be said to breed true, as 



