Vererbung, Variation, Mutation. 93 



fashion. The sources of error are chiefly in the recording of many red and 

 whites or dark roans as reds. The writer, with Laughlin, regards roan a mosaic, 

 but also considers it a simple dominant pattern consisting of an irregulär ar- 

 rangement of red and white hairs. It varies in amount of white within itself, 

 hinting at the fact that it is probably not a single unit but complex. The ex- 

 pected and actual results obtained when a homozygous red self-colored animal 

 is crossed with a homozygous white are discussed. Roan and red are both com- 

 plieated by Spotting patterns. Roan is entirely separate from certain types of 

 patterns (those on flanks, withers, sides and back, rump, thigh and Shoulder) be- 

 cause it behaves as a distinctly segregating unit, although it is possible that other 

 patterns (white markings on leg, face, front or distinct body spots) may not show 

 except in presence of roan. Pearl. 



232) Youiig, C. C. ? Strange Sheep of Asiatic Russia. In: Amer. Breeder's 

 Mag., Vol. IV, Nr. 4, S. 184—192, 1913. 



The author describes some of the peculiar types of sheep exhibited at the 

 first national sheep congress in Moscow, in 1912. Crosses between fat-tails and 

 broad-tails were shown from the Caucasus, which had excellent mutton and could 

 endure any amount of hardship. Of this type the most noteworthy were the 

 Erik, Bozach, Mazech, Karabach, Lezguik, Osetui, Avar, Tushin and 

 Kjara. The Karakul, Voloshskaja, Kalmit, Reshetilev, Sokoliev and 

 the Bessarabian Tshushka were some of the most interesting sheep exhibited. 

 It was conceeded by the breeders present that all of these sheep except possibly 

 the Kalmik when crossed with Karakuls would greatly gain in weight, besides 

 giving excellent skins. Hybrids exhibited from crosses of fat-rump on long-tail 

 were heavier than Lincolns, which are the heaviest sheep in America and Eng- 

 land. Hybrids which were said to have resulted from crossing Grade Arabi and 

 native wild goat were noteworthy for the luster of the lamb skins, but were 

 very wild. Pearl. 



233) Castle, W. E. ? Some new varieties of rats and guinea-pigs and 

 their relation to problems of color inheritance. In: Amer. Natur., 

 Bd. 48, Heft 2, S. 65—73, 1914. 



This paper describes two new colour varieties of rats which have recently 

 appeared in England. One of thern, a black-eyed yellow rat, was caught on a 

 ship at Liverpool and hence probably came from abroad. This is the first time 

 that yellow has occurred in rats, though yellow varieties of many other mam- 

 mals are known. 



The other new variety is a pink-eyed agouti. These new varieties have 

 both been taken up by fanciers, from whom Castle has obtained individuals 

 for breeding purposes. Both varieties when crossed with other rats are recessive, 

 and hence they have both evidently originated through negative or retrogres- 

 sive mutations. The bearing of there facts is discussed, and predictions made 

 of 6 as yet unknown varieties which should now be obtained by crossing of the 

 new types. The author considers that albinism in mammals is probably due to 

 a loss of the ability to form yellow pigment, of which black and brown are 

 merely- higher Oxydation stages. Gates. 



234) Sollas, I. B. J., Notes on the offspring of a Dwarf-bearing strain 

 of Guinea-pigs. In: Journ. of Genetics, Bd. 3, Nr. 3, S. 201—204, 1914. 



In a previous paper (Reports to Evol. Com. Royal Soc. 1909) Miss Gollas 



