THE PHENOMENA OF MUTATION 177 



Morgan emphasises the statement that a factor 

 does not affect only one particular organ or part of 

 the body. It may have a chief effect in one kind of 

 organ, e.g. the wings or eyes, but usually affects 

 several parts of the body. Thus the factor that causes 

 rudimentary wings also produces sterility in females, 

 general loss of vigour, and short hind legs. 



The facts to which I shall refer concerning (Eno- 

 thera are for the most part quoted on the authority 

 of Dr. Ruggles Gates, and taken from his book The 

 Mutation Factor in Evolution (London, 1915). The 

 occurrence of mutations in (Enothera was first 

 noticed by De Vries, the Dutch botanist, in the 

 neighbourhood of Amsterdam in 1886. He found a 

 large number of specimens of (Enothera Lamarck- 

 iana growing in an abandoned potato-field at Hil- 

 versum, and these plants showed an unusual amount 

 of variation. He transplanted nine young plants 

 to the Botanic Garden of Amsterdam, and culti- 

 vated them and their descendants for seven genera- 

 tions in one experiment. Similar experiments have 

 been made by himself and others. The large 

 majority of the plants produced from the (E. Lamarck- 

 iana by self-fertilisation were of the same form 

 with the same characters, but a certain percentage 

 presented ' mutations ' that is, characters different 

 from the parent form, and in some cases identical 

 with those of plants occurring occasionally among 

 those growing wild in the field where the observa- 

 tions began. Nine of these mutants have been 

 recognised and defined, and distinguished by different 

 names. The characters are precisely described and 

 in many cases figured by Gates in the volume cited 

 above. The first mutant to be recognised in 1887 



M 



