E.M. Brock 1957 Interspecific Reactions 1 ARL, Barow, Northern Alaska Aug 4 A young male lemming weighing 23.0 gr and brought in from Barow Village July 31 was placed in a different aquarium than it had been in before. The Lemmus has been solitary since July 31 when it was brought in along with 9 unweaned young (see Lemmus, sp. act.) A minute after the Lemmus had been placed in this aquarium, Microtus oeconomicus weighing 31.2 grams was placed in the aquarium. The Microtus has been living solitarily in an aquarium ever since it was brought back from Nerle River where it was caught on June 18. This female Micotus gave birth to at least two young the first day it was at Barow since the next morning, remains of two new born young were found in the aquarium. Immediately after the two animals recognized one another, it appeared that the small or lemming tried to bite the Micotus on the rump. Then immediately the lemmings