June 8, 1906.] 



SCIENCE. 



867 



Much that is observed as to plant life is 

 true also of animal life, giving a faeies by 

 which Merriam's austral regions may be 

 characterised. 



In all discussions of this environment, 

 little or no attention has been paid to the 

 eifeets of light, which is here at its maxi- 

 mum. Without entering into detail as to 

 the physiological sequelae of light from 

 other parts of the spectrum, the rays from 

 the violet end may be considered. These 

 rays affect all life submitted to them in a 

 harmful manner by checking or prohibit- 

 ing cell growth or metabolism. It will be 

 found that many of the protective features 

 of xerophilous plants and of animals which 

 are attributed to aridity, rarefied air, soil, 

 etc., are adaptations due to avoidance of 

 dangerous rays of light. This is to be 

 noticed in the habit of some delicate plants 

 which thrive in the shade of hardy plants, 

 the protective covering and nocturnal hab- 

 its of animals, and the architecture and 

 shelter instincts, as well as skin color of 

 the ancient and modern Indians who lived 

 in caves, cliff shelters or cavate houses, or 

 whose pueblos as a whole or as to the indi- 

 vidual houses were constructed to admit a 

 minimum of light, but from far different 

 causes, though still environmental pueblos 

 were generally oriented with reference to 

 the east; first, for the utilitarian purpose 

 of receiving the early morning sun, grate- 

 ful after the chilly nights of the high 

 regions ; and second, on account of the im- 

 portance of the rising sun in heliolatry. 



Such were the general features of the 

 great area under consideration and on the 

 whole the characteristics are constant to the 

 present time, but it is difficult to realize 

 the immense modification of animal and 

 vegetal life which the white man has 

 wrought in this region during the thirty 

 years of his active occupancy. At the be- 

 ginning of this period the region was well 

 grassed and supplied with other vegetation 



adequate to the needs of vast herds of ante- 

 lope, elk and deer; rodent animals and 

 birds were plentiful and carnivores had 

 abundance of prey. As a result of vegeta- 

 tion a humus had formed on all protected 

 situations, rainfall was absorbed and equal- 

 ized in distribution and the terrific denuda- 

 tion which gashes the land at present was 

 not begun. 



The country was adapted to grazing and 

 especially favorable on account of tempera- 

 ture and latitude, and at once great herds 

 of cattle, horses and sheep were introduced 

 from Texas where pasturage had failed. 

 The result was that the range became over- 

 stocked, the grass disappeared under the 

 tongues and hoofs of myriads of domestic 

 animals; shrubs and trees were browsed 

 and destroyed or swept away by fires ; from 

 certain regions species of plants vanished; 

 and the land lay bare to the augmented 

 winds and torrential rains. Trails became 

 profound arroyos, the humus vanished 

 into the streams and the surface of the 

 country was stone, sand and gravel. Not 

 the least of this baneful influence was the 

 drying up of springs and other sources of 

 water, and more than one observer col- 

 lected data going to prove the progressive 

 desiccation of the pueblo region. These 

 facts must be borne in mind in discussion 

 of the environment of the southwest. As 

 an example, it may be stated that in the 

 exploration of one ancient pueblo at Wins- 

 low, Ariz., the bones of thirty-seven species 

 of animals were taken from the house 

 refuse; it is not probable at present that a 

 naturalist could collect five of these species 

 from the environment. Wherever the ex- 

 plorer's spade has been put into the ancient 

 ruins, facts of this character come to his 

 notice, even if he has not heard the story 

 from the early settlers or Indian tradition- 

 ists. 



There is no doubt that cycles of dry and 

 wet seasons occur in the southwest, but the 



