Likening one energy machine to another, the thyroid may be compared to the accelerator of an automobile.

I gave the thing the cream of the Wooster brain all the way down, but it continued to beat me what could have caused the outbreak of hostilities, and I bunged my foot sedulously on the accelerator in order to get to Aunt Dahlia with the greatest possible speed and learn the inside history straight from the horse's mouth.

Some of the glands of internal secretion act as accelerators to the sex glands.