358 APPENDIX 



opmental stages, and relicts should be used to interpret extension of range be- 

 yond the limits of the biome. 



7. The distribution of the principal food plants or animals must be ascer- 

 tained. 



The greatest importance is to be attached to habitat relations. This must 

 be learned particularly with reference to early serai stages or climax and late 

 subclimax stages of vegetation, as the primary classification of influents has 

 practically to be based upon these considerations. 



The quantitative methods used in water are numerous, and the reader 

 should consult Abderhalden's Handbuch; Juday (1916, 1926); Ward and 

 Whipple (1918); Reighard (190S); Ekman (1911); Needham and Christen- 

 sen (1927); Moon (1935); and Williams (1936). 



