THE AXIAL GRADIENTS IN HYDROZOA. VIII. RESPIRATORY DIFFERENCES ALONG THE AXIS IN TUBULARIA WITH SOME REMARKS ON REGENERATION RATE

¹ HULL ZOÖLOGICAL LABORATORY, UNIVERSITY OF CHICAGO

1. The rate of oxygen consumption per unit volume of cnosarc is greater in apical than in basal halves of distal regions of the stem of Tubularia.

2. The rate of oxygen consumption per unit volume of cnosarc is greater the younger the stem (smaller its diameter).

3. The time between cutting and completion of oral hydranths is shorter the more apical the piece in pieces of equal length from distal levels of the stem of Tubularia.

4. The statement in 3 may or may not hold for proximal regions of the stem, depending on the species.

5. The time between cutting and completion of oral hydranths is independent of the length of the piece when the apical end of the pieces is taken at the same level, except in very short pieces.

6. The time between cutting and completion of oral hydranths is shorter the younger the stem (smaller the diameter).

7. The size of the regenerated oral hydranths is almost entirely independent of the length of the piece, when the apical end of the pieces is taken at the same level, except in very short pieces.

8. The size of the regenerated oral hydranth is slightly smaller especially as to width the smaller the diameter of the stem but not proportionally smaller.

9. The size of the regenerated oral hydranth is absolutely larger on apical than on basal pieces of equal mass taken from distal regions of the stem.

10. In general there is a relation between respiratory rate and regeneration. The higher the respiratory rate the shorter is the time interval between cutting and completion of oral hydranths and the larger is the size relatively or absolutely of the regenerated oral hydranth.