602 R. S. LULL VARIATIONS OR SPECIFIC DISTINCTIONS: WHICH? 



were captured near Nairobi, British East Africa, and confined in the 

 Washington Zoo for five or more years, changed in color so much, increas- 

 ing with each successive molt, that they finally resembled that of the race 

 F. leo nyanzce of the more humid Victoria Nyanza region. 2 Beebe 3 ex- 

 perimented on birds, increasing the pigmentation with successive molts 

 by confining them in a superhumid atmosphere. The inference is that 

 with both birds and lions the color change was due to the direct effect of 

 humidity, as that of Washington is notably greater than of the Nairobi 

 region of Africa. The park-reared animals also had much longer, finer 

 manes and elbow tufts than did wild-killed lions of the same race. 



Another effect of environment on the Washington lions is, however, 

 more pertinent to our thesis, for in this case it took the form of a mus- 

 cular and bone response to a change of living habits, due to the fact that 

 the park-reared animals were fed on man-killed food and were not re- 

 quired either to kill or carry off their prey. Thus Hollister says (page 

 190): 



"The skulls of lions and other large carnivores which habitually kill quanti- 

 ties of heavy game are greatly influenced in a definite way by the development 

 of the principal muscles used in gripping, holding, tearing, biting, and shaking. 

 If the animals are captured when young and reared in confinement, these par- 

 ticular muscles are little developed and the bone at the region of origin or 

 insertion is little changed by their influence. The bones then retain certain 

 characteristics of juvenility and develop along wholly different but uniform 

 lines from that of the wild-reared animal. 



"Changes in the skull which would be accepted as of 'specific' or possibly of 

 'generic' value in wild animals from different regions are thus produced in the 

 life of a single individual within from five to seven or eight years, almost as 

 rapidly as if by 'mutation.' .... Might some such change not happen in a 

 state of nature? ... If all the ungulate mammals of Africa, or in some 

 one extensive region, were swept away in a few years by a plague like the 

 rinderpest, would the lion die out, or would he completely change his habits in 

 one generation and become a feeder on mice, squirrels, birds, and fruit? In 

 the latter case, would not the enforced disuse of the powerful mechanism for 

 the destruction of zebras, hartebeest, and larger game produce in one genera- 

 tion, as with the park lions, a type of skull wholly different from that now 

 known in a state of nature?" 



The specific changes seen in the park lions were greater relative and 

 actual zygomatic breadth, large rostra, great distance across the base of 

 the skull at the mastoids. While actually measuring less in condylobasal 

 (greatest) length than many of the wild massaica skulls of. equal age, 



2 N. Hollister : Proc. U. S. Nat. Mus.. vol. 53. 1917, pp. 177-193. 



3 C. W. Beebe : Zoologia, vol. i, no. 1, 1907. 



