NOTES AND LITERATURE 



NOTES ON HEREDITY AND EVOLUTION 



Mendel, in his investigations, found certain Hieracium hy- 

 brids which did not split up in the second generation. The 

 writer several years ago suggested that the cause of this phe- 

 nomenon might be found in apogamy. Ostenfeld 1 has recently 

 shown that in a large number of species of this genus apogamy 

 exists. It therefore seems probable that the constancy of these 

 hybrids is due to the omission of the reduction division. 



Pearl and Surface 2 have recently published some very in- 

 teresting contributions on inheritance as a result of studies of 

 crosses made between Barred Plymouth Rock poultry and Corn- 

 ish Indian Games. It was found that eggs produced by the 

 cross Barred Plymouth Rock males on Cornish Indian Game 

 females gave a larger per cent, of fertile eggs than the recipro- 

 cal cross ; also a larger per cent, of fertile eggs than either pure 

 breed produced. The low percentage of fertile eggs in the cross 

 in which the Barred Plymouth Rock female was used, the au- 

 thors suggest, may possibly be due to unfavorable environment 

 for Cornish Indian Game spermatozoa in the Barred Plymouth 

 Rock oviduct. 



There was also a higher per cent, of fertile eirus hatched for 

 the hybrids than for either pure breed, this result being attrib- 

 uted to the greater vigor of the hybrids. 



The Barred Plymouth Rock breed is one which has high egg- 

 laying quality, while the Cornish Indian Game has low egg- 

 laying quality. The very interesting result was obtained that 

 hybrids produced by using Barred Plymouth Rock sires were 

 good layers, thus showing that the high laying quality was 

 transmitted by the Barred Plymouth Rock sire. On the other 

 hand, hybrids produced by using Barred Plymouth Rock fe- 

 males did not possess the high laying quality, thus indicating 



1 Ostenfeld. C. II.. "Further Studies m, Am^mv ana TT v Vim A 4 caH mi nf 



