It is virtually axiomatic that no predatory species (other than modern man) exterminates its own food supply. Long ago nature must have established a fairly definite ratio between the populations of the Wolf and the Caribou. Although a certain fluctuation of that ratio could be expected from time to time, each fluctuation would be followed by a return to more or less normal conditions. The trend of evolution has doubtless been toward perfecting the Wolf in its ability to capture the Caribou, but at the same time toward perfecting the Caribou in its ability to escape the Wolf. Unequal progress of this sort on the part of the two species would presumably have been rather disastrous to the one or the other. But it is nature’s way to have preserved a proper balance between the abilities of the two species, and thus between their populations. This balance (a rather delicate one) has probably been upset to some extent by the advent of civilized man with his devices to the Barren Grounds. The Caribou “exemplify the survival of the fittest; none but the perfect are allowed to live and breed, hence their perfection. We believe that the wolf is in no small degree responsible for this high standard, and that were he killed off the species as a whole would suffer.” (Critchell-Bullock, 1930: 161.) “It is doubtful if the efforts of white or native hunters are of any importance whatever in the control of wolves in the caribou country, or could, under present circumstances ever be of any importance.” (Clarke, 1940: 109). _References._--Franklin, 1823: 242, 327, 344, 486, 487; John Ross, 1835a: 402, 530, 534, 564; Back, 1836: 128-129; Simpson, 1843: 232; Armstrong, 1857: 395, 480-481, 488, 525; Osborn, 1865: 227-228, 231, 232; Kumlien, 1879: 53, 54; Gilder, 1881: 61; Bompas, 1888: 60; Collinson, 1889: 244; Pike, 1917 (1892): 56-58; Whitney, 1896: 239; Jones, 1899: 374-375; Preble, 1902: 41, and 1908: 214; Hanbury, 1904: 89; MacFarlane, 1905: 692-693; Amundsen, 1908, +1+: 102; Seton, 1911: 225-226; R. M. Anderson, 1913b: 516; Stefánsson, 1913a: 93, and 1921: 248-249, 475-476; Blanchet, 1925: 34; Mallet, 1926: 79; Birket-Smith, 1929 (1): 51; Seton, 1929, +1+: 344-346, and +3+: 108-109; Blanchet, 1930: 54-55; Critchell-Bullock, 1930: 159-162; Hoare, 1930: 22; Kitto, 1930: 89; Jacobi, 1931: 240-241; Harper, 1932: 31; Sutton and Hamilton, 1932: 33, 35, 36, 81, 82, 84, 85; Ingstad, 1933: 157-159, 165-166, 207, 302-304, 306-307; Hornby, 1934: 106, 108; Freuchen, 1935: 93, 120-122; Murie, 1939: 245; Clarke, 1940: 107-109; Manning, 1942: 29, and 1943a: 55; Downes, 1943: 262; Young, 1944: 236-238, 243; Yule, 1948: 288; Harper, 1949: 230-231, 239; Banfield, 1951a: 37-41; Anonymous, 1952: 263-265. _Relations to birds of prey_