No pure strains, so we can't make new mixes ourselves.

This looks like a bird of paradise, a pure strain from an ancient stock.

This section presents information that is used in the selection of pure strains for breeding.

The most rewarding opportunities are derived from seed of a pure strain.

"I just want a pure strain of psychiatric judgment."

The women kept the different strains pure as they cultivated the corn.

It's all theory on my part, but here, I think, we have the pure strain.

A pure strain of song floated up from the river - whether human or animal was hard to tell.

A pure strain which has yet to be equaled in this sector of space.

Green eyes like those of the girl, the driver, everyone else on the planet who had been reared from the pure strain.