6 ANIMAL ECOLOGY 



similar needs in the cell or cells which compose 

 the animal body. The mere statement of the facts 

 of such relations is enough to make valid such a 

 comparison. 



For the associational aspect of ecology the German 

 naturalist, Mobius, proposed in 1877 the term "bio- 

 coenosis." The meaning of this he expressed very 

 clearly and concisely, and on account of its relatively 

 obscure publication, in a paper devoted to oyster 

 culture, it has not gained the circulation among 

 zoologists which its importance merits. His state- 

 ment (Mobius, '83, p. 723) is as follows : 



"Every oyster-bed is thus, to a certain degree, a 

 community of living beings, a collection of species, 

 and a massing of individuals, which find here every- 

 thing necessary for their growth and continuance, 

 such as suitable soil, sufficient food, the requisite 

 percentage of salt, and a temperature favorable to 

 their development. Each species which lives here 

 is represented by the greatest number of individuals 

 which can grow to maturity subject to the conditions 

 which surround them, for among all species the 

 number of individuals which arrive at maturity 

 at each breeding period is much smaller than the 

 number of germs produced at that time. The total 

 number of mature individuals of all the species living 

 together in any region is the sum of the survivors of 

 all the germs which have been produced at all past 

 breeding or brood periods ; and this sum of matured 

 germs represents a certain quantum of life which 

 enters into a certain number of individuals, and which, 



