TRANSACTIONS OF SECTION D. 603 



3I0NDA y, A UG UST 6. 

 Joint Discussion with Section K on Fertilisation. 



The following Papers were read : — 



1 . Breeding Experiments in Canaries : an Exception to Mendel's Law. 



By C. L. "W. NooBDuiJN. 



The experiments carried out by the writer of this paper lead him to regard 

 the results of crossing two varieties or of crossing a variety with a species to be 

 determined, not solely by the nature of the characters united, but also by the 

 length of time through which each of the two characters concerned has existed. 

 According to the strict Mendelian the result of mating a variety with its parent 

 species is the same whether the union takes place in the generation in which the 

 variety arises or a hundred generations later. It is the opinion of the author 

 that, in varieties which have recently arisen, the power of transmitting their 

 own characters is weak, while the tendency to revert is great, when the melo- 

 morphs with which we are dealing are not ' colour ' and ' absence of colour,' but 

 two colours. 



Two wild canaries caught in Teneriffe were crossed with cinnamons, 

 variegated yellows, and clears. The result of the first of these crosses was like 

 the wild canary in nestling feathers, and up to the first moult. Of the second 

 of the crosses the young were like the wild canary in nestling feathers, but 

 some had white feathers in the tail and wings and a yellow belly. 



The oftspring of the cross ' wild ' x * yellow ' were all variegated yellows, 

 about half of the body being covered with yellow feathers. Now the yellow 

 canary has existed as such for about 360 years ; and the inference is that the 

 transmission of yellow, when a yellow is mated with a wild, is due to the length 

 of time for which it has existed. 



Preliminary Note on a Neio Conception of Segregation. 

 By A. D. Darbishire, M.A. 



3. The Evolution of the Cock's Comb. By J. T. Cunningham, M.A. 



The theory of natural selection is a theory of the origin of adaptations or of useful 

 characters. It was originally called a theory of the origin of species, but it has not 

 been proved that specific characters are useful or adaptive. The theory, if true, 

 should be applicable to particular characters; for example, the cock's comb. 



This appendage in the wild species is a secondary sexual character; it is of no 

 use to the bird in its ordinary life. It therefore comes under the subordinate 

 theory of sexual selection. It must, therefore, be useful or ornamental in court- 

 ship or combat. There is not sufficient evidence to convince us of its importance 

 as an ornament, and in combat it is not only useless, but harmful. This latter pro- 

 position is more especially supported by the fact that in the sport of cock-fighting 

 it was the usual practice to ' dub ' the birds, i.e., to cut off" comb and wattles. 



Then the comb and wattles, being a secondary sexual character, are not 

 developed in the females in the wild species, or are very rudimentary in them. 

 The mere preservation or selection of variations would not account for the failure 

 to transmit them to the hen. Similarly, selection does not account for the fact 

 that the comb is not fully developed until the bird is sexually mature. The 

 hypothesis that the comb was an outgrowth, originally due to the laceration of 

 the head in the combats of cocks, would give some reason for the peculiarities 

 mentioned. 



A third view of the origin of characters is that they arose fully developed, 

 Spontaneously, without selection or influence of external conditions. On this 

 view the phenomenon is not explained. But there is not yet sufficient evidence 



