514 



THE COMMUNITY 



and of Forbes (1887), noted previously." 

 The first of these showed a food chain 

 of at least four links: house cats— field 

 mice— bumblebees— red clover. It will be 

 remembered that the cats preyed upon 

 the mice, the mice destroyed the bee combs, 

 and the bees gathered nectar from the 

 clover flowers and cross pollinated them in 

 a mutuahstic relationship. Darwin sums up 

 this part of the food web by stating (p. 

 69): "Hence it is quite credible that the 

 presence of a fehne animal in large numbers 

 in a district (as a consequence, in this in- 

 stance, of the house cat's commensaHsm in 

 man's society) might determine, through 

 the intervention first of mice and then of 

 bees, the frequency of certain flowers in 

 that district!"t 



* We are concerned here witli general 

 tendencies, principles, and concepts discover- 

 able in food chains and food webs. The in- 

 terested student will find food chain or food 

 web diagrams and data in the following 

 references: Ant nests (O. Park, 1929, 1932, 

 1935a); caves (Park, Allee, and Shelf ord, 

 1939, pp. 117-126); forests (Adams, 1915; 

 Allee. 1926a; Blake, 1926; Park, 1931a; Park 

 and Strohecker, 1936; Seton, 1909; Shelford, 

 1913; Weese, 1924); fungi (Park, 1931a); hot 

 springs (Brues, 1927); lakes (Bond, 1933; 

 Klugh, 1927; Shelford, 1913; Welch, 1935); 

 prairie (Adams, 1915; Carpenter, 1940a; 

 Clements and Shelford, 1939; Elton, 1927; 

 Graham, 1939; Haviland, 1926; Hayes, 1927; 

 Isely, 1938a; Seton, 1909; Shackleford, 1929; 

 Shelford, 1913); rotting logs (Graham, 1925; 

 Savely, 1939; Shelford, 1913); sand desert 

 (Buxton, 1923; Kashkarov and Kurbitov, 

 1930); seas (Bond, 1933; Chace, 1940; Coker, 

 1938, 1947; Hardy, 1924; Sverdrup, Johnson, 

 and Fleming, 1942; Russell and Yonge, 1928, 

 Chap. 9); tortoise burrows (Hubbard, 1893); 

 tundra (Haviland, 1926; Summerhayes and 

 Elton, 1923). 



Data and numerous references on bio- 

 coenoses, communities, and isolated food-link 

 relationships will be found in Chapter 26 of 

 this section of the book. The following refer- 

 ences give a vast amount of food chain ma- 

 terial: general (Brelxm, 1911; Lydekker, 1901; 

 Williams, 1928; Hesse, Allee, and Schmidt, 

 1937); birds (McAtee, 1932); insects (Brues, 

 1946; Comstock, 1933; Essig, 1942; Folsom 

 and Wardle, 1934; Imms, 1924; Metcalf and 

 Flint, 1939); mammals (Hamilton, 1939; Seton, 

 1909); vectors and parasites (Belding, 1942; 

 Harms, 1939; Riley and Johannsen, 1938). 



t McAtee ( 1947 ) emphasizes the fact ( un- 

 known to Darwin) that honeybees are im- 

 portant to the pollination of red clover, and 



The concept of interdependence of feed- 

 ing categories has long since lost its novelty. 

 Darwin, in "The Origin of Species" (1859, 

 Chap. 3) stated, nearly a century ago:" 



"Every one has heard that when an Amer- 

 ican forest is cut down, a very different vegeta- 

 tion springs up; but it has been observed that 

 ancient Indian ruins in the Southern United 

 States, wliich must formerly have been cleared 

 of trees, now display the same beautiful diver- 

 sity and proportions of kinds as in the sur- 

 rounding virgin forests. What a struggle must 

 have gone on during long centuries between 

 the several kinds of trees, each annually scatter- 

 ing its seeds by the thousand; what war be- 

 tween insect and insect— between insects, snails 

 and other animals with birds and beasts of 

 prey— all striving to increase, all feeding on 

 each other, or on the trees, their seeds and 

 seedlings, or on the other plants which first 

 clothed the ground and thus checked the 

 growth of the trees. Throw up a handful of 

 feathers and all fall to the ground according 

 to definite laws; but how simple is the problem 

 where each shall fall compared to that of the 

 action and reaction of the innumerable plants 

 and animals which have determined, in the 

 course of centuries, the proportional numbers 

 and kinds of trees now growing on the old 

 Indian ruins!" 



This passage by an early ecologist, pub- 

 Hshed a decade before the term was pro- 

 posed by Haeckel, is prophetically modern 

 in content. While it lacks the recent co- 

 emphasis of cooperative agencies operating 

 with competitive agencies in bringing about 

 community organization, and the concept of 

 community self-maintenance, there are sev- 

 eral present day viewpoints eitlier implied 

 or stated. For example, we find in this 

 quotation (1) retrogressive succession of a 

 part of a community, with eventual recti- 

 fication in frequency and density of species; 

 (2) competition for food; (3) food web; 

 (4) two of the three basic concepts used 

 to describe the interplay of species within 

 a community; and (5) the treatment of 

 communities as being in a state of flux, 

 tending, through time, toward a condition 

 of balance. 



From what has been said of unbalance in 

 the community, it is obvious that impair- 



attacks this Darwanian food chain consequently, 

 wathout impairing the general principle ex- 

 emplified. 



" A. L. Burt reprint from the 6th London 

 edition, p. 69, 



