THE harvest mouse, Micromys minutus, is easy to keep in captivity, this tiny beast flourishing in a roomy cage as many naturalists have proved. One of mine lived with me for nearly four years and died apparently of senile decay. But it has rarely been bred in confinement; indeed I believe that until quite recently the late Miss Phyllis Kelway's achievement of breeding a litter of harvest mice was unique. I say until "quite recently" because two females in my possession have just produced a litter each. The first family two thirds grown was out and running about on May 12 and the second litter came out, being but half-grown, on May 15. An accurate count was difficult for the small animals kept running in and out of the straw, hay, etc., in their quarters; but my provisional estimate was three in litter number one and four in litter number two. This may have to be modified.