Allgemeine Biologie und Entwickelungsiehre. 19 



dominance of the latter condition "is not always perfect". Albino individuals 

 may transmit either complete or partial pigmentation, or may be heterozygous 

 with respect to these two characters, although in none of these cases do they 

 themselves show any trace of pigment. With reference to pigment inheritance 

 gray is dominant over all the other color types (with the possible exception 

 of yellow). Gray coat color may be produced synthetically by breeding to- 

 gether a black and a golden-agouti animal. Black, chocolate and golden-agouti 

 individuals usually breed true. Black and possibly golden-agouti may be domi- 

 nant over chocolate. All of these 3 color types may arise by a resolution of 

 the compound character gray. For detailed results the original paper must 

 be consulted. 



Castle ( 4 ) in a long memoir, describes in detail his results on the inheritance 

 of the color and other characters of the coat in Gavia and Lepus cuniculus. 

 Finds in C. three pairs of alternative coat characters which obey Mendel's 

 law: (a) albinism is recessive to pigmented coat; (b) smooth coat is recessive 

 to rough coat (in rough coated C. the hair is in part arranged in rosettes 

 "between which the hair, sloping in opposite directions, forms a series of 

 ridges or crests"); (c) long or "Angora" coat is recessive to short coat. Since 

 the smooth coat is undoubtedly an ancestral character while the rough coat 

 is a recent acquisition these results indicate that "ancestral characters are not 

 necessarily dominant over new characters in heredity". In L. , (a) and (b) 

 were found to hold as in C. , but since the "rough" coat is unknown in L. 

 no further evidence on (c) could be obtained. The author sharply distinguishes 

 between latent and recessive characters. The term "recessive" is used in 

 the strict Mendelian sense, while characters normally dominant which have 

 disappeared in recessive gametes are designated as "latent" characters, e. g., 

 pigment characters may be latent in albinos. "Latency" may possibly explain 

 some cases of deviation from simple Mendelian expectation. Recessive indi- 

 viduals may in some cases be prepotent. The "lop-eared" condition in C. is 

 not inherited according to Mendelian principles. The author points out various 

 ways in which cross-breeding between dominant and recessive individuals may 

 lead to the production of new forms. Considerable space is given in the paper 

 to a critical discussion and interpretation of Darbishire's results on inheritance 

 in Mus. 



Spillman discusses the Mendelian inheritance of the horned and polled 

 condition in Bos. States that ordinarily the character of being polled is do- 

 minant over the character of being horned. On this basis he shows how it 

 would be possible to breed a race of pure polled animals, starting with but 

 a few such individuals in the herd. 



Davenport has analyzed the heredity data given in A. G. Bell's "Sheep 

 Catalogue", and comes to the conclusion that "black wool colour in sheep be- 

 haves like a Mendeliau recessive characteristic". 



Mumford reports the results of experiments on Ovis designed to determine 

 what factors influence the size of the animal at birth. He finds that still- 

 born young are much smaller than the average for the young born alive. 

 Young having a heavy birth weight grow after birth on the average more 

 rapidly than do those with a low birth weight. The size of the male parent 

 is not a controlling factor in determining the size and weight of the young at 

 birth. The size of the young is positively correlated with the size of the 

 mother. Q? are heavier at birth than Q. The birth weight of twins is not 

 widely different from that of single young. 



