190 MY POULTRY DAY BY DAY 
cockerels of the mating will on the other hand sire high-laying 
pullets. 
In introducing fresh blood beware of violent outcrosses—that is 
to say, the incoming male bird should be related in some degree 
to the stock. Otherwise there is a danger of sterility, or partial 
sterility. The “unrelated cockerel’” so often advertised is a 
delusion and a snare. Fortunately it is almost impossible to get 
a wholly unrelated cockerel, as the main strain of blood flows 
through most of the egg farms of England. A severe outcross 
may also introduce broodiness where, by selection, it had almost 
been obliterated. The non-sitting hen is a production of artificial 
selection, and any in-coming of purely unrelated blood may cause 
a return to broodiness. 
A popular fallacy is to regard the mating of two pure breeds (a 
first cross) as a uniting of the virtues of both breeds. Very rarely 
it is. Sometimes it is a mixture of the virtues and defects of both 
breeds and frequently it misses all the virtues and awakens the 
long-concealed faults of a remote ancestor. What we call pure 
breeds are the result of certain crossings that occurred either 
recently or remotely. These crossings have crystallised into a 
fixed type, with special characteristics, probably unlike those of 
their ancestors, but the moment you introduce alien blood you 
provide a key to unlock the latent characters of these remote 
ancestors, and more often than not those long dormant traits 
are of an undesirable kind. Thus it is that, if you begin to cross, 
the result of the mating may be birds having little or nothing in 
common with their parents but possessing much that was common 
to their very remote ancestors. If you double-cross you will get 
characteristics further away and further back in ancestry, and 
this repeated will land your stock in the condition of the early 
fowls that laid only two clutches of eggs per year. The first cross, 
if well considered, is safe enough as a rule, but the plunge into the 
past which a crossing brings about should never be carried further. 
The male birds of a cross should always be killed and not bred from, 
while the pullets may be mated again to a pure breed of the same 
variety as the male parent. 
