1903.] 



IX FAXCY MICE AXD RATS. 



89 



Lastly two pairs gave both greys and yellows, thus :— 



Patches. 

 Pair. Grey. Yelloio. 



XII 2 3 



LXXXIV 5 4 



In the origmal account and in the discussion of the f acts h}^ 

 Professor Weldon in 'Nature,' the ofispring of the 2 J tamiiies 

 Tre efe^iJ to as having consisted of a mixture of greys, yelows 

 :ndbici:; and the fact that only certain ^^-^^^^^ 

 and certain families yellows, and that no family 8^J^,J^*^*^^^^^^^^^ 

 and vellows, is not emphasised. We can conceive that botii 

 y oitd i3lacks .night\. associated with greys when fawxrs 

 Ire crossed with albinos, but till_ the phenomenon occurs it need 

 nni-, bp considered in this connection " . s ^.^ ^ 



"°k p oceed with the fundamentally ^^^^^^ 

 purity of the coloured race, we are mformed .hat the oiigma 

 SzLs were bred together for some --f « .--^|trteS 

 offsnrino' like themselves. The number of individuals thus tested 



f S mimber of offspring raised .^--^1'"".?^:^ o^I'l^ ^- 

 we may conclude that they were considerable. /^ ^^/^ ' 1\7;^^^^^^^^^^ 

 regard this evidence of purity m the hght of the facts p.oMdea 

 by the six famines which gave either yellows or Slacks J!^ P«^^^ 

 ceive that if "fawn" is dominant to yellow and to black, the 

 occuri^nce of yellows and blacks in the crosses with albino is 

 Sly explained. We have in fact only ^o. -PP- ^^f ..^ 

 family 27 the coloured mother, and m families 77, 78, ^o the 

 coloured fathers, contained 6^«c^ ; and ^"-^^^^^'^'-^^^^l^^^^ 

 the coloured fathers contained y.Wo^o ; and ^^ flV^.n^^ 

 clear The chance of seeing the impurity by merely ciossing 

 awns together would not be very great. Most of ^hem -ide^^Y 

 were pure, and since black X yellow ^^''''^}''^^ ^Ztlt he 

 din-Y fawn heterozygote, the impurity would probably not be 

 emJnstrated unlesl^fawns containing black ^ to^ther^ 

 fawns containing yellow bred together. By breeding the mothei 

 of family 27 with the father of 77, 78, or 85, some te.t of th.. 

 su^estio^n might have been made. Of course we have as yet 10 

 d?ect experimental proof that fawn is dominant to black and to 

 y 1 ow biit since saSes can throw blacks, and since - -ts gey^ 

 Ld- white is dominant to black-and-white, it seems very possible 

 that these " fawns" may also have been thus dominant. 



* When a compound character is crossed uith ^^-^^^ ^^SsT 1)7"^- 

 that com.ponents of the compound appeal- alre^d^^^^^ 



example,! have seen the " walnut comb ot t^fPf,^^-^/^^?!^^^, table union) crossed 

 ducedby synthesis of rose-comb and Pe'^-'^°i;^^,^\',^;f!,,"ye fas some single. Such 

 with single comb g ve somejose some pea ome s alnut ^^^^^^^^ ^lonolepsis (" false 



^^= ■^^S'z^SStSS^rtSa^^^^^ will P^bably not 



reproduce the excluded elements in their posterity. 



