i857.] VARIABILITY. 459 



or comparing variability in plants from the great general 

 variability of parts. I should look at the law as more com- 

 pletely smashed if you would turn in your mind for a little 

 while for cases of great variability of an organ, and tell me 

 whether it is moderately easy to pick out such cases ; for if 

 they can be picked out, and, notwithstanding, do not coincide 

 with great or abnormal development, it would be a complete 

 smasher. It is only beginning in your mind at the variability 

 end of the question instead of at the abnormality end. Per- 

 haps cases in which a part is highly variable in all the species 

 of a group should be excluded, as possibly being something 

 distinct, and connected with the perplexing subject of poly- 

 morphism. Will you perfect your assistance by further con- 

 sidering, for a little, the subject this way ? 



I have been so much interested this morning in comparing 

 all my notes on the variation of the several species of the 

 genus Equus and the results of their crossing. Taking most 

 strictly analogous facts amongst the blessed pigeons for my 

 guide, I believe I can plainly see the colouring and marks of 

 the grandfather of the Ass, Horse, Quagga, Hemionus and 

 Zebra, some millions of generations ago ! Should not I 

 [have] sneer[ed] at any one who made such a remark to me 

 a few years ago ; but my evidence seems to me so good that 

 I shall publish my vision at the end of my little discussion on 

 this genus. 



I have of late inundated you with my notions, you best of 



friends and philosophers. 



Adios, 



C. Darwin. 



C. Darwin to J. D. Hooker. 



Moor Park, Famham, June 25th [1857]. 



My Dear Hooker, — This requires no answer, but I will 

 ask you whenever we meet. Look at enclosed seedling gorses, 

 especially one with the top knocked off. The leaves suc- 

 ceeding the cotyledons being almost clover-like in shape, 



