1890 PHYSIOLOGICAL SELECTION 171 



account of Wallace desiring to answer it. For my 

 own part I thirik that all this fire of criticism at the 

 present juncture is a mistake. As yet the theory is 

 only a ' suggestion,' and, imtil tested, there can be no 

 adequate data for forming a definite opinion. 



Therefore I regret the pubHshed opposition — those 

 who are in favour do not publish only because it may 

 tend to choke ofi co-operation in carrying out the ex- 

 periments ; and it was for the sake of securing assist- 

 ance in so laborious a research that I pubhshed the 

 suggestion in outline. 



I wonder who Catchpole is ? HJis answer in 

 ' Xature ' to Wallace won't do. 



Tours very truly, 



Geo. J. EoMANEs. 



18 Cornwall Terrace, Eegent's Park, JJ.W. : January 7, 1887. 



Dear Darwin, — Some time ago you write that I 

 ought to read a book or paper by Jordan about varieties 

 in relation to sterihty. I cannot find any book or 

 paper of his at the L.S. Kbrary which treats of this 

 subject ; could you give me the name of his essay ? 



I am making arrangements for trying whether 

 there are any degrees of sterility to be found between 

 well-marked and constant varieties of plants. But 

 as I have never done anything in the way of hybrid- 

 ising, perhaps you would be good enough to let me 

 know whether the enclosed plan of experimenting 

 represents the full and proper way of going to work. 

 I know that you do not beKeve in the object of it, 

 but, even supposing it to be a wild goose chase, there 

 would be no harm in your telling me the best way to 



