350 



VICTOR E. SHELFORD. 



munities are those which are normal to a given geographical 

 area, while the secondary communities are those produced by 

 cultivation or other activities of man, and are maintained only 

 by cultivation, reverting to the primary types as soon as the 

 cultivation ceases. They therefore represent ecological experi- 

 ments with the essential records usually entirely lacking, and 

 with the habits of the species constituting them undetermined, 



hed tih thyr eghreth bgrti 

 rty dbhty fbhtygfh dbgfty 

 dftr fgythrtg bfgtyr hufgk 

 fgvcyhtuyfgtry vbgft rytgm 

 cvdfrterfdyhtub vnhgythubb 

 bcvfdtxnzxdfcrtfbhtgydbfgg 

 vb fnhtbgfy fgyr bfgvdftrt 

 bfgtrybdbfghty vbft dgtrxd 

 vbgf tg fbgtyhyuijghb f nb 

 dfcrgtryhfy vbgfhty dbgfty 

 cbvfghtygdtfrnvkjgh fbgtb 

 cvfdgfbt nhkzxdscxgczkzkvg 

 bfgtyhr dftrgtybvhfgiingvb 

 dfcrg cgbfhty du bkbkbbgfh 



FIG. 7. 



Showing the arrangement 

 of plants and animals on a 

 plot of ground under pri- 

 meval conditions, each letter 

 representing several closely 

 associated plants and ani- 

 mals. 



edge rftfgyrhtubfhgtybgft 

 fecdftrybthuginf dvgfhytb 

 cbaaaaaaaaaa bf 

 ed aaaaaaaaaaed 

 fg aaaaaaaaaa fg 

 dcaaaaaaaaaadc 

 eb aaaaaaaaaa dg 

 fd aaaaaaaaaa fd 

 dc aaaaaaaaaa dc 

 fe aaaaaaaaaa fe 

 eg aaaaaaaaaa eg 

 fc aaaaaaaaaa fc 

 cgnvdftrgghhfgdbfbdgtrycg 

 gfzcvdg cvbdg fvgty ggd b 



FIG. 8. 



Showing the arrangement 

 under agricultural condi- 

 tions. Some of the original 

 groups are to be found 

 along the fence rows. 



so that until the primary communities have been thoroughly 

 investigated, the value of such experiments cannot be ascer- 

 tained. Failure to recognize the division into primary and 

 secondary is responsible for much of the confusion in the matter 

 of environmental relations of animals in general, but more 

 especially of land animals. 



When civilized man first enters a new territory, he destroys or 

 attempts to destroy, large game which threatens him and his 

 domestic animals. He then destroys the natural vegetation and 

 incidentally many other animals, by clearing the timber and 

 burning all woody debris, and plowing and putting out plants 

 which are entirely new to the region. Under primeval conditions 



