Varietäten, Descendenz, Hybriden. 103 



of pigment; the inheritance of the albino Charakter in crosses between 

 coloured forms and albinos is however of the usual type. 



The qualitative results of all the crosses which have been made 

 are consistent with the scheme of factors proposed; not only so, but 

 in two cases the results ot crosses, previously unknown, were cor- 

 rectl}^ predicted from it. But on the other band, the quantitative 

 results obtained in some cases diverge somewhat from those expected, 

 so that for the present the scheme must be regarded as tentative. 



Supernumerary Mammae. 



Guinea-Pigs possessing supernumerary mammae have not been 

 uncommon. The inheritance of the character does not show either 

 clear dominance or recession. It arises in the olTspring of normal 

 parents, and when two animals possessing the character are mated 

 together, they bear young, some of which are normal, while others 

 have the extra mammae. But the character may also pass over a 

 generation, the normal j^^oung of abnormal parents giving again 

 abnormal young. 



Dwarfs. 



This Variation appeared in the first instance in some of the 

 offspring of apparently normal parents. D warf offspring have appeared 

 in two families which were not known to be related, but as söme 

 of the ancestors of both families were obtained from the same fancier, 

 there is a possibility, or even probability, of remote relationship. 



The Variation affects the entire framework of the animal. The 

 skeleton shows that all the bones of the trunk and limbs are shorter 

 and stouter than those of the normal guinea-pig, and in het skull, 

 the basi-cranial axis and the face very much shortened. 



The pedigrees given show that the power of producing some 

 dwarfs among the offspring is transmissible, and the incidence of 

 the character shows remarkable sex-ratios: the various families in 

 which they have occiired have given : 



normal offspring dwarf offspring 



25 49 5 20 



The evidence is however not yet sufficientl}^ complete to allow 

 of analysis. R. P. Gregory. 



Wheldale, M. Further Observations upon the Inheritance 

 of Flower-Colour in Antirrhinutn majus. (Rep. Evol. Comm. 

 Roy. Soc, London, V. p. 1-25. 1909.) 



The original wild Antirrhinum majus has magenta flowers the 

 colour being due to a pigment of the anthocyanin class. The pro- 

 duction of this pigment depends upon the presence in the Zygote 

 of certain organic substances, accompanied probably by certain 

 ferments, all representable by Mendelian factors. The magenta 

 anthocyanic pigment may be looked upon as an oxidation product 

 of a chromogen allied to the flavone series of colouring matters; 

 the oxidation is probably brought about by the action of an oxydase. 

 The loss of power to produce the oxydase in any plant gives rise 

 to a variety bearing ivory-white flowers. A variety bearingyellow 

 flowers arises from the ivory-white by the loss of a further consti- 

 tuent, possibly a ferment. The yellow chromogen, if acted upon by 

 an oxydase, gives rise to a crimson anthocyanin, as compared 

 with the magenta anthocyanin which results from the oxidation of 

 the ivory-white chromogen. Complete absence of any chromogen 



