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Journal of Experimental Biology 34,425-446 (1957)
Published by Company of Biologists 1957

Components of Nitrogenous Excreta in the Earthworms Lumbricus Terrestris, L. and Eisenia Foetida (Savigny)

A. E. NEEDHAM ¹

¹ Department of Zoology and Comparative Anatomy, University Museum, University of Oxford

1. Up to one-half of the nitrogen excreted by both Eisenia and Lumbricus is protein, probably mucus. A high percentage of the remainder is urea and ammonia.

2. Leaf as food spares body nitrogen and reduces the total output of nitrogen, in three species of earthworm examined. A nitrogen-free diet of filter paper has little nitrogen-sparing action in Lumbricus.

3. The pattern of excretion of nitrogen compounds by Lumbricus, and especially the ratio ammonia/urea, varies with food-intake and this is the major factor found to affect the pattern.

4. Food causes an increased acid production by Eisenia and Lumbricus. The latter neutralizes this by increasing its output of ammonia, and decreasing that of urea.

5. The decrease in urea output is much greater than the increase in ammonia output, indicating some degree of independence between the two mechanisms.

6. When Lumbricus and Eisenia are kept in water, changes in volume, or in frequency of renewal, of the medium have little effect on the rate of output of ammonia or of urea, though the worms are affected by the accumulation of excreta in the medium.

7. By contrast to the nitrogen compounds, acid is liberated in proportion to the volume of the medium.

8. Eisenia differs from Lumbricus in the following respects: (a) it has a much higher specific output of total nitrogen and of the ammonia fraction; (b) ammonia constitutes a higher percentage of the total; (c) ammonia output does not decrease but increases when fasting; (d) it excretes considerable amino nitrogen; (e) it excretes more uric acid; (f) it has a higher specific output of acid and uses a non-nitrogenous base, possibly CaCO₃ from the calciferous glands, to neutralize much of this; (g) it makes little use of urea in the control of pH, or as a form of nitrogen excreted; (h) filter paper causes a considerable reduction in nitrogen output.

9. Allolobophora caliginosa has the Lumbricus pattern of output, with values of specific output much lower than those of Lumbricus itself.

10. Isolated posterior pieces of Lumbricus and Eisenia have a pattern of nitrogen output similar to that of feeding worms, but those of Allolobophora have the pattern of fasting worms of the species.