terms pure and strain:
The definition of pure according to my Webster's New World Dictionary is as follows: 1) free from anything that adulterates or taints; 2) unmixed; 3) of unmixed stock or pure-blooded; 4) that which is pure.
The definition of strain according to my self same dictionary is also as follows: 1) ancestry, lineage; 2) the descendants of a common ancestor; race; or stock line; 3) a line of individuals differentiated from its main species or race by certain generally superior qualities; 4) an inherited character or tendency.
Our working definition for a pure strain would, therefore, of necessity be as follows: An ancestry or lineage; the descendants of a common ancestor or stock line differentiated from its main species or race by generally superior qualities, inherited character, or tendency; unmixed, free from anything that adulterates or taints.
Now, if memory serves me correctly, the racing pigeon is the product of the mixing together of several different breeds of pigeons including Horseman, Dragoon, Smerle, the carrier pigeon, and others. In different countries, different pigeon breeds formed the base from which the fanciers worked to develop their homing pigeons to lesser or greater degrees of perfection-usually lesser. The modern racing pigeon is therefore a hybrid and therefore not a pure breed at all.