STIMULATING EFFECTS OF CROWDING 



179 



confusum, that will develop, Chapman found, as was stated earlier 

 (chap, vii), that with these animals and with this medium it is pos- 

 sible to demonstrate that the total population per gram of flour 

 arrives at a constant level of 43.97 ± 2.88. Chapman's table record- 

 ing the population level attained at successive intervals when 2, 4, 

 8, 16, 32, and 64 beetles are placed in 32 grams of flour for each lot is 

 repeated here as Table XIII. 



TABLE XIII 



Showing the Number of Beetles per Gram of Flour with Initial Population 



Varying from 2 to 64 per 32 Grams. The Results Are Given 



IN Terms of Beetles per Gram of Flour 



(From Chapman) 



Chapman is interested in showing by these figures, as by those 

 cited in chapter vii, that, regardless of the initial seeding, a point of 

 equilibrium is reached after which the population remains relatively 

 constant. His medium is distinctly advantageous in this respect, for 

 with the Protozoa which we have just been considering, after the 

 similarly constant point of equilibrium is reached, the population 

 declines on account of the changes induced in the culture medium. 

 In flour beetles, as we have said before, this decline can be controlled 

 by changing the culture medium. 



Our own interest is in examining the effect of numbers in the ini- 

 tial population upon the early rate of reproduction. The relation- 

 ships existing for the 11- and 25-day periods shown above are given 

 in Figure 13, which has been drawn from the data just given. The 

 figure shows immediately that for these first periods in the develop- 



