x Preface 



one advantage which no other line of scientific inquiry 

 possesses, in that the special training necessary for 

 such work is easily learnt in the practice of it, and 

 can be learnt in no other way. All that is needed is 

 the faithful resolve to scamp nothing. 



If a tenth part of the labour and cost now devoted 

 by leisured persons, in this country alone, to the 

 collection and maintenance of species of animals and 

 plants which have been collected a hundred times 

 before, were applied to statistical experiments in 

 heredity, the result in a few years would make a 

 revolution not only in the industrial art of the breeder 

 but in our views of heredity, species and variation. 

 We have at last a brilliant method, and a solid basis 

 from which to attack these problems, offering an 

 opportunity to the pioneer such as occurs but seldom 

 even in the history of modern science. 



We have been told of late, more than once, that 

 Biology must become an exact science. The same is 

 my own fervent hope. But exactness is not always 

 attainable by numerical precision : there have been 

 students of Nature, untrained in statistical nicety, 

 whose instinct for truth yet saved them from perverse 

 inference, from slovenly argument, and from misuse 

 of authorities, reiterated and grotesque. 



The study of variation and heredity, in our ignor- 

 ance of the causation of those phenomena, must be 



