10 BOARD OF AGRICULTURE. [Pub. Doc. 



and wliite have not made a blend in hybrids, but liave main- 

 tained their distinctive qualities. This is explained by the 

 fact, discovered by Mendel in the middle of the last century, 

 that when the reproductive cells are ready for fertilization 

 they consist of only one set of factors ; that is to say, any egg 

 cell that is ready for fertilization may carry the red color 

 or the white color, but not both. The partnership that has 

 existed in the hybrid animals is broken up in the reproduc- 

 tive cells, and white and red are separate again as in the 

 original pure-bred animals. 



These reproductive cells that are ready to unite and form 

 a new individual are called " gametes." The process by 

 which the cell divides and arranges all these factors, so that 

 no two that are antagonistic are found in any one gamete, is 

 extremely interesting as well as complex. 



Let us now see what will happen when the reproductive 

 cells from this cross form gametes. Each complete cell will 

 contain both red and white because the red Durham was 

 bred to the white Hereford. As far as color is concerned, 

 therefore, we may denote the constitution of the cell by 

 WrK, making the r small because it is recessive, in that it 

 disajipears in the jDresence of white. When this cell divides, 

 however, to form the marrying cells, or gametes, the white 

 and the red separate and no gamete contains them both. This 

 will be true for both egg and sperm cells, and the gametes 

 containing white will be found in the same numbers as those 

 containing red. When they are ready to unite there will be 

 equal numbers of red and white gametes, and a red will have 

 as good a chance of combining with a red as it will with a 

 white, and the white will have as good a chance of combining 

 with a white as with a red. 



If numbers enough are used, therefore, the oifspring will 

 be pure reds or mixed reds and whites or pure whites. The 

 mixed reds and whites will all show white faces because the 

 white is dominant over the red. Therefore, there will be 

 three whites to one red. The reds will all breed true to red 

 if bred together, because the white has been lost out of their 

 cells and they will breed as true as if they had never been 



