700 SUMMARY OF CURRENT RESEARCHES RELATING TO 



is recessive to perfect crest. The yellow canary is derived from the 

 original green canary by the loss of black. It carries a mottling factor. 

 Consequently when the yellow canary is crossed with a pigmented canary 

 or with a finch, the hybrids are mottled. 



The mottling is not a fixed pattern. The spots vary in position and 

 relative size ; they may cover nearly the whole body or they may form a 

 mere "ticking." The degree of mottling is inheritable. Ticking 

 behaves as a nnit-character. Mottling is a heterozygous character and 

 throws mottled, clear yellow, and self -greens. 



The principle of localisation of the units of a complex plumage must 

 be recognised. The cap of the Lizard canary, the red face of the gold- 

 finch, the shoulder-striping of the green canary, are not only unit- 

 characters, but they occur only at their proper localities and in their 

 proper forms in the body plumage. In mottled canaries the presence of 

 black on the shoulder means striping, on the wing it means dead black 

 white-laced remiges, on the mid-breast it means a uniform olive colour. 

 The plumage of a yellow canary may be compared with a letter that has 

 been written with invisible ink. Wherever the developer acts (i.e. the 

 black pigment of the green canary is added) that which is written 

 appears with all of its idiosyncrasies. 



Transmission of Coat-characters in Rats.* — G. P. Mudge finds 

 that albinos breed true to albinism, whether their ancestry is pigmented 

 or not. Albinos which appear to be identical in their coat-character may 

 be in reality quite different. The author's exjeriments give " an ocular 

 demonstration of the actual presence of the coat-pattern in albinos," 

 and the interpretation is corroborated by breeding results. 



It is further shown that when a piebald black rat is mated with a 

 similar one, two classes of offspring may be obtained. One of these 

 contains all black piebalds, and the other a mixture of black piebalds 

 and albinos in nearly equal numbers. 



When a piebald black rat is mated with an albino, it may be said 

 that, so far as the author's experiments have gone, five different results 

 may be obtained : (1) the offspring are all black piebalds ; (2) they 

 may be a mixture of black piebalds and albinos ; (3) they may be all 

 " Irish " forms ( = black self-coloured) ; (4) they may be a mixture of 

 albinos, black piebalds, and " Irish " ; (5) they may contain albinos, 

 " Irish," and a grey form. "It can be shown that the divergence of 

 the results obtained when two individuals apparently similar are mated 

 is due to the gametic nature of the albino employed." 



Transplantation of Ovaries.t — F. H. A. Marshal and W. A. Joly, 

 experimenting chiefly with rats (in one case with a monkey), find that 

 ovaries are more readily transplanted into the kidney than on to the 

 peritoneum ; that homoplastic transplantation (within the same animal) 

 is easier than heteroplastic transplantation (to another animal) ; that 

 the latter seems to be easier when the animals are near relatives ; that 

 the presence of an animal's own ovaries does not seem to exert any 

 inhibitory influence on the successful attachment and growth of 



* Proc. Roy. Soc, Series B, lxxx. (1908) pp. 388-93. 



t Quart. Journ. Exp. Physiol., i. (1908) pp. 115-20 (1 fig.). 



