THE SIZE OF THE BODY AND THE SIZE OF THE ENVIRONMENT IN THE GROWTH OF TADPOLES

¹ From the Physiological Laboratory, The University of Rochester School of Medicine and Dentistry, Rochester, N. Y.

1. Growth of the tadpole under optimal conditions is very slow between fertilization and hatching, proceeds with logarithmic increase of bulk for about two weeks, and then declines in rate up to the beginning of metamorphosis.

2. The crowding of many individuals together causes little change in the initial rate of logarithmic increase, but brings on the decline in rate much sooner and more severely than in isolated individuals. The same effect results from decrease in the volume of water in which the tadpoles live.

3. Experimental analysis of the mechanism of the crowding effect shows that the composition of the water it self has no significant influence on growth. The full effect of crowding is manifested in rapidly running water, but not when the individuals are partitioned from one another. A similar inhibition of growth results from agitation of the tadpoles.

4. The ingestion of food per individual is much reduced by crowding. The effect is therefore exerted upon the behavior of the tadpole toward food. The effect is precisely graded with respect to the density of crowding, so that it is accurately correlated with the physical size of the environment. It possibly serves as an example of the inhibitions through which growth is ordinarily regulated.

This article has been cited by other articles:

				H. M. Wilbur and J. P. Collins Ecological Aspects of Amphibian Metamorphosis: Nonnormal distributions of competitive ability reflect selection for facultative metamorphosis Science, December 28, 1973; 182(4119): 1305 - 1314. [Abstract] [PDF]