60 'WHAT IS A SPECIES?' 



same thing would have happened to me on any scheme 

 of work.' ! 



The essentially subjective character of the results 

 reached by the systematist stands out with remarkable 

 force in this as in other passages of Darwin's letters. 



A few years later, on July 30, 1856, he wrote to the 

 same friend: — 'I differ from him [Lyell] greatly in 

 thinking that those who believe that species are not 

 fixed will multiply specific names : I know in my own 

 case my most frequent source of doubt was whether 

 others would not think this or that was a God-created 

 Barnacle, and surely deserved a name. Otherwise I 

 should onlv have thought whether the amount of differ- 

 ence and permanence was sufficient to justify a name.' 2 



Disregarding for the moment the term species, it is 

 convenient to consider the various groupings of individual 

 animals and plants. 



1. Forms having certain structural characters in 

 common distinguishing them from the forms of other 

 groups. Groups thus defined by the Linnaean method 

 of Diagnosis may be conveniently called Syndiagnostic 

 {(tvv, together ; Sidyucoai?, distinction). 



2. Forms which freely interbreed together. These 

 may be conveniently called Syngamic (criv, together ; 

 ydfios, marriage). Free interbreeding under natural 

 conditions may be termed Syngamy ; its cessation or 

 absence, A syngamy (equivalent to the Amixia of Weis- 

 mann). 3 



1 Life and Letters, vol. ii, p. 40. 



2 Ibid. vol. ii, p. 81. 



3 The history of the term Syngamy, although brief, has been re- 

 markable. By a curious coincidence this very word was independently 

 proposed by my friend, Professor Marcus Hartog, of Queen's College, 

 Cork, in order to express that fusion of the essential reproductive elements, 

 or gametes, which has been generally known by the inconvenient and 

 in many ways misleading term fertilization. Prof. Hartog suggested 

 the word (Sept. 14, 1903) in introducing a discussion on fertilization in 

 Section D (Zoology) at the meeting of the British Association at Southport. 

 The Report of the meeting (p. 693) only prints the names of the speakers. 

 I was not at the Southport meeting, and never heard the word until it 

 was suggested as suitable for my purpose by Mr. Arthur Sidgwick. 



