. The ecology and life history of the common frog (Rana temporaria temporaria) . Fig. 4. The Apparatus Used for the Experiments on the Reactions of Young Tadpoles to Deficient Oxygen under the influence of a stimulus) and a negative geotaxis (a movement upwards) when once movement was provoked by lack of oicygen. Transferring the results of the experiments to the field, it is now possible to explain what happens. The tadpoles in the central parts of the large aggregations live in water with very little oxygen. They therefore swim upwards. Those at the edges of the aggregation are in better-oxy
. The ecology and life history of the common frog (Rana temporaria temporaria) . Fig. 4. The Apparatus Used for the Experiments on the Reactions of Young Tadpoles to Deficient Oxygen under the influence of a stimulus) and a negative geotaxis (a movement upwards) when once movement was provoked by lack of oicygen. Transferring the results of the experiments to the field, it is now possible to explain what happens. The tadpoles in the central parts of the large aggregations live in water with very little oxygen. They therefore swim upwards. Those at the edges of the aggregation are in better-oxygenated water, and, not being stimulated, do not swim at all. The colony therefore remains in the same place as a whole, but the individual members of it are continually changing places. When there are only a few clumps, there is enough oxygen for all, and no swimming takes place. All that is seen in such cases are the gymnastic exercises that tadpoles of this age execute wliile they hold on v^th the aid of the adhesive gland with which they are provided. The Function of the External Gills The water of these places has another unusual feature. It is full of the gelatinous remains of the envelopes, and during the determinations
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Keywords: ., bookcentury1900, bookcollectionbiodiv, booksubjectranatemporaria
