the Species as a Geyic-complex. 115 



we shall be in a better position to discuss the behaviour of 

 the various characters and to decide wliether linkage is 

 present. 



In the meantime, the discussion whether tiiere aio two 

 " species '^ or one in this case is probably placed in its true 

 perspective. In the first place, we see that the species-concept 

 is too rigid to apply to sucii a variety of indeterminate 

 character-associations. Even if we single out the extreme 

 associations and oppose them under different names, we are 

 merely confusing the issue by stressing the extremes and 

 ignoiingthe more indeterminate combinations. In the second 

 place, we do not know whether these particnlar extreme 

 associations are analogous to others in which linkage occurs, 

 though we miglit be tempted to predict from the combinations 

 found in the field that they are not. 



Summary. 



(1) There is urgent necessity for the investigation of the 

 " species ^"^ as a character-complex. The subject should be 

 studied both from its genetic and its morphological aspect. 



(2) The character-complex is a fact of common knowledge. 

 Viewed at the morphological level it varies extensively in its 

 components, exhibiting a correlated system of non-transgres- 

 sive characters or showing a large variety of combinations 

 which include transgressive characters. 



(3) The future method of investigation should be an 

 attempt to discover whether linkage occurs in such 

 associations, and, if so, to what extent. 



(4) Improved morphological and genetic investigation of 

 the degree to which the complex is represented in individuals 

 is likely to show that any attempt to distinguish rigid cate- 

 gories among associations of such variable constitution is a 

 very imperfect representation of the relations between 

 organisms. The ^* species ^' concept, as far as we can see 

 without further investigation along these lines, appears to be 

 applicable to only a certain type of combination. 



Works quoted. 



(i) Bateson. ^ Problems of Genetics.' 1913. 



(2) BoETTGER. Zool. Jalirb. xliv. Syst. 1921. 



(3) Kleiner. ^'Untersucliung-en am Genitalapparat von H. Jiemoralis 



uud Jiortensis.'^ Inaugural Dissertation. Zurich. 



(4) Lang. ' Ueber die Bastarde von H. horteyisis und //. ncmoralis.' 



Jena, 1908. 



(5) Morgan. "The Physical Basis of Heredity.'' (Monographs on 



Experimental Biology.) 1911. 

 RoBSox. Proc. Zool. Soc. 1921. 



S* 



