Mahch 19, 1920] 



SCIENCE 



285 



obvious that many iiniversities and colleges, 

 by virtue of their locations and resources, have 

 abundant opportunity to perform valuable 

 work in the ecology of vertebrates. 



Although for some of the more detailed re- 

 searches in the physiology, chemistry, habitat 

 relations and psychology of animals a con- 

 siderable amount of apparatus is necessary, 

 investigations of the highest importance may 

 be carried forward with relatively simple 

 equipment. The field is sufficiently compre- 

 hensive to afford promising opportunities to 

 any sincere and resourceful student with 

 proper training. 



Suggestions as to equipment needed in the 

 different lines of work indicate the wide lati- 

 tude of choice open to the prospective investi- 

 gator. For the prosecution of field work there 

 should be provided camp outfit, traps and col- 

 lecting materials, photographic apparatus, bal- 

 ances and if possible, equipment for field study 

 of habits, such as shovel, axe, trowel or large 

 spoon, brush cutter, tape-line, sketch pad, co- 

 ordinate paper, and writing materials. For 

 more detailed study of the habitat apparatus 

 such as thermometers and thermographs, wet- 

 bulb thermometers and psychrographs, rain 

 gauges, geotomes, etc., are required. Investi- 

 gations of the chemistry and physiology of the 

 animals in question call, of course, for special 

 equipment; and in connection with many of 

 the studies it is necessary to provide some 

 cages, pens, yards or other enclosures for 

 breeding and keeping terrestrial vertebrates 

 under close observation. 



The richness and attractiveness of the field 

 may be amply demonstrated through the sim- 

 ple device of a tentative program of work.- It 

 is fully realized, I may add, that a program of 

 research may be outlined with comparative 

 ease, but that it is often relatively difficult to 

 get results. But the drawing up of this pro- 

 gram, embracing, as it does, material for many 

 investigations, is doubtless justified in that it 

 indicates the immensity of the field, implies 

 the necessity for widespread cooperation in 



2 I am indebted to Dr. Frederic E. Clements, of 

 the Carnegie Institution of Washington, for help- 

 ful suggestions in this connection. 



the exploration of its resources, and points 

 out some comparatively neglected fields of re- 

 search in vertebrate zoology which are full of 

 promise. 



I. Close analysis of the animal community. 



1. Community reactions. 



(a) Origin. 

 ( 6 ) Migration. 



(c) Invasion and reinvasion. 



(d) Establishment. 



(e) Competition. 

 (/) Dominance. 

 (g) Extinction. 



2. Primary and secondary succession in the 



animal community. 

 (a) Primary succession as illus- 

 trated by zonation in se- 

 lected localities. 



(1) In deserts. 



(2) In areas of moderate hu- 



midity. 



(3) In regions of excessive hu- 



midity. 

 (6) Secondary , succession as illus- 

 trated by results of inter- 

 ference with the natural 

 balance by man. 



(1) Permanent changes in ani- 



mal population. 



(2) Esiuvasions of abandoned 



(3) The animal assemblages 

 of over-grazed areas; of 

 areas denuded by de- 

 forestation ; of forest 

 burns ; of flooded areas ; 

 of drained areas; of re- 

 claimed areas in gen- 

 eral. 



(c) CUmax assemblages of animals. 



(1) Significance for game pro- 



tection. 



(2) Significance in animal 



control. 



(d) Factor control of distribution 



and succession among ani- 

 mals. 



(1) Physical factors. 



(2) Biotic factors. 



3. The animal commumty and climatic 

 cycles. 

 (1) Interrelations with forest repro- 

 duction. 



