n] Colours of Animals 45 



Lina lafponica. Two forms occur, one having elytra spotted with 

 black on a brown ground, while in the other the elytra are entirely black. 

 The latter is recessive, and the formation of the brown pigment in the 

 ground is thus due to a dominant factor. McCracken (189, 199). 



Melasoma (Lina} script a. A totally black form was found to be re- 

 cessive to the spotted type. Two intermediate conditions may occur, one 

 of which may be a homozygous type (see original). McCracken (191). 



Gastroidea dissimilis. Two forms, either deep blue-black, or shiny 

 bright green. The latter is recessive. Curious complication as regards 

 numerical results. McCracken (190). 



Leptinotarsa decemlineata (Colorado potato beetle). Evidence obtained 

 by Tower (266, pp. 275-9) indicates that a variety called by him pallida 

 behaves as a recessive. The var. melanothorax of the species L. multi- 

 taeniata also proved to be a recessive to its type (ibid. pp. 284, 292, 293). 

 Various other more complex phenomena are recorded (q. v.). 



Crioceris asparagi (Asparagus beetle). Each elytron has three yellow 

 areas or spots on a blue-black ground. The upper spot is sometimes 

 united to the middle one. This condition proved to be recessive to that 

 in which the spots are separate, but all intermediate conditions occur 

 [being presumably heterozygous]. Lutz (182). 



MOLLUSCA. 



Helix hortensis and H. nemoralis. The unbanded variety is dominant 

 to the banded types in both the species, sometimes completely, some- 

 times partially. Generally also red ground-colour is dominant to yellow or 

 brown, but this effect may dimmish with age of the hybrid individual. 

 Lang (167-9). For details as to hybrids between the two species see 

 (169). 



As regards dominance of colours very little in the way 

 of general rule can yet be predicated, nor till the chemistry 

 of pigments is much better understood is it likely that such 

 general rules will be discovered. It may, however, be 

 remarked that actual albinism, the total absence of pig- 

 mentation, is always, so far as we know, a recessive 

 character in both animals and plants. Curious cases never- 

 theless are known both in animals and plants where a 

 partial whiteness, which we should a priori imagine to be 

 a kind of albinism, behaves as a dominant^. Another fact 

 of a somewhat paradoxical nature is to be seen in the 

 behaviour of some of the very deep colours, red and purples, 

 characteristic of the flowers and other parts of some garden 

 strains. These more intense colours both in Primula 

 Sinensis, in the Stock, and in the Sweet Pea (and doubtless 



* See Chap. v. 



