G H Cale's ideas are outlined clearly in the Hive and the Honeybee
(1975 edition):

> The final evaluation of any inbred line must rest upon its performance in cross or hybrid combinations. Only a few lines out of many tested are retained because only a *few* show superior performance as hybrids.

> When ordinary inbred lines are crossed, the progeny in some cases fail to show heterosis (hybrid vigor). More than that, with ordinary inbred lines there is no clear-cut way to achieve highly desirable lines that are compatible with each other during the inbreeding process.

> The value of heterotic effects in a bee-breeding program depends upon the demonstration that hybrids may be formed having a greater productivity than the normally available honey bees. The average honey yields of the hybrids was 106 %.

He goes on to state:

> one must conclude that enormous opportunities in bee breeding are at hand.

-- 
Peter L. Borst

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