COMPETITION AND ECESIS 261 



276. Competition quadrats. Practically any permanent quad- 

 rat will serve for the field study of competition. Denuded quad- 

 rats are especially good, though they need to be followed for a 

 number of years. When rapid results are sought, a denuded 

 quadrat is used for a competition culture by planting it in the 

 manner desired. Other quadrats are used in a somewhat similar 

 fashion by sowing the seeds of a. weed or other vigorously grow- 

 ing species among the original occupants. Interesting results are 

 obtained with annuals by using a decimeter quadrat. Two (juad- 

 rats of this size are staked side by side in a family of seedlings, 

 and the number of individuals counted for one of them. The 

 plants are then removed from one, taking care to leave two or 

 three scattered ones undisturbed. As they develop, the behavior 

 of the plants in the two quadrats indicates clearly the effect of 

 competition. 



Experiment 66. Competition. Make a simple and a mixed culture in 

 the manner indicated, using Helianthus, Datura, or other vigorous 

 plants. Follow the development of each culture carefully, noting the 

 differences of form and structure, and determining the relation to light, 

 and also to water if this is possible. Allow the plants to go to seed, 

 and determine the largest and smallest seed production for those that 

 flower. Permit one example of each culture to become permanent for 

 study during the following year. 



Stake out two decimeter quadrats in the family of an annual, such 

 as Polygonum aviculare, just after the seedlings appear above the 

 ground. Count one quadrat and thin out the other. Compare the 

 development in the two throughout the season. Note the size and 

 number of mature plants in each, and the number of seeds produced. 



277. Ecesis. Ecesis is the adjustment of a plant to a new 

 place or a new habitat. It includes all the phenomena shown 

 by a migrant from the time it enters a new situation until it be- 

 comes thoroughly established there. It is the decisive factor in 

 invasion, since migration is of no value unless followed by it. 

 The interaction of the two is intimate. Migration is usually fol- 

 lowed by ecesis, which then establishes a new center from which 

 further migration is possible, and so on. 



Ecesis depends in a large measure upon the time, direction, 

 rapidity, distance, and amount of migration. The time of year 

 in which fruits mature and distributive agents act has a marked 

 influence upon the establishment of a species. Seeds which 



