Mecho-Products, its manufacturer, had lavished attention on this jaw-construction. It was their trademark, their unique feature. Their ads, their brochures, stressed the massive frontal scoop mounted on all their models. And there was an optional assist: a cutting edge, power-driven, that at extra cost could easily be installed in their "Luxury-line" models.

This blue Nanny was so equipped.

Moving cautiously ahead, the blue Nanny reached the fence. It stopped and carefully inspected the boards. They were thin and rotted, put up a long time ago. It pushed its hard head against the wood. The fence gave, splintering and ripping. At once the green Nanny rose on its back treads, its grapples leaping out. A fierce joy filled it, a bursting excitement. The wild frenzy of battle.

The two closed, rolling silently on the ground, their grapples locked. Neither made any noise, the blue Mecho-Products Nanny nor the smaller, lighter, pale-green Service Industries, Inc., Nanny. On and on they fought, hugged tightly together, the great jaw trying to push underneath, into the soft treads. And the green Nanny trying to hook its metal point into the eyes that gleamed fitfully against its side. The green Nanny had the disadvantage of being a medium-priced model; it was outclassed and outweighed. But it fought grimly, furiously.

On and on they struggled, rolling in the wet soil. Without sound of any kind. Performing the wrathful, ultimate task for which each had been designed.

"I can't imagine," Mary Fields murmured, shaking her head. "I just don't know."

"Do you suppose some animal did it?" Tom conjectured. "Are there any big dogs in the neighborhood?"