GENERAL TOPICS IN INHERITANCE. 



Now, by hypothesis we should expect a difference in iuheritaace in these 

 characteristics as indicated below : 



Of the five cases where, on de Vries's theory, we should expect non-Men- 

 delian results, No. 4 is apparently not Mendelian, No. 5 gives often a 

 mixture of characters, Nos. i and 2 apparently give true Mendelian domi- 

 nance and recessiveness, No. 3 is still doubtful. Of the .six cases in which 

 a Mendelian inheritance is looked for, we certainly find it in three cases and 

 less certainly in the others. On the whole, there is a slight but not a striking 

 difference in transmission between the two sets of characteristics, and I can 

 only conclude that for poultry, so far as I can see at present, de Vries's 

 formula does not hold universally. 



inhb:rit.\nce of positive vs. negative varietai, characteristics. 



According to de Vries, when an individual having a certain characteristic 

 patent is crossed with one in which it is latent the patent characteristic is 

 dominant, the latent recessive. Do results with poultry confirm this law ? 



In the following table the patent characteristic is given in the left-hand 

 column and the dominant characteristic in italics : 



1. Nasal process of premaxillary, «(j;vo?i' High nostril. 



nostril. 



2. Closure of cerebrum completed ; />/(n'w Failure of cerebrum to close; cerebral 



head. ! hernia. 



3. Crest : black crest feathers Smooth head ; white crest feathers. 



4. Complete devetopinent of the feather . . Interrupted development of the feather ; 



silky feather. 



5. Tail Taillessness. 



6. Pigmented plumage Albinism in plumage. 



7. Red ii<ing bar Uniformly colored wing. 



8. Shafting Plain feather. 



Of the foregoing eight characters, seven clearly follow the law that patent 

 characteristics dominate over latent. No. 6 is a clear exception, for since 

 all the wild Galliu?e are deeply pigmented birds it can hardly be doubted 

 that white is a negativ-e variation in which color is latent. However, the 

 exception (No. 6) is not universal, for while plumage does not always domi- 



