According to this way of thinking, one knows what DUCK is because ducks have something in common — their duckness categorized according to how they walk, talk, and so on.

It has been known for some years past that Piroplasma in the digestive tube of an adult female tick can give rise to infection in the offspring of that female, so that one generation of ticks can acquire the parasites from cattle, and the next generation can transmit the disease to other cattle

And in the British Isles, there were the shepherd-type dogs already mentioned, an ancestral houndlike dog and a small house dog that could have later given rise to the terriers.

Many programs were written for the Sinclair Spectrum computer in BASIC.