Quarterly Journal of Microscopical Science, Vol s3-91, 401-418, Copyright © 1950 by Company of Biologists

Determination of the Form of Regenerating Limbs in Asellus aquaticus

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

1. The nerve-supply to the regenerating anterior pleopods of Asellus aquaticus influences the rate of regeneration but not the character of the regenerate.

2. The tissues of the locality of the blastema determine the character of the regenerate and also influence the rate and extent of regeneration.

3. In contrast to the thoracic limbs these appendages are very sensitive to the induction of abnormalities of regeneration.

4. The complete suppression of regeneration of a limb is the most common induced abnormality. An all-or-none effect is evident.

5. The development of supernumerary structures is the next most common abnormality.

6. The re-emergence of the endopodite of the first pleopod, suppressed in normalontogeny, is the most frequent supernumerary. It often shows homoeotic differentiation.

7. A tendency towards bilateral symmtery is evident in all abnormalities, in spite of asymmetry in experimental treatment.

8. Fusion of individual blastemae is not uncommon. There is no fusion with homoplastic embryonic tissue.

9. There is no substance with the properties of a ‘wound hormone’.

10. The regeneration of PI. 2 in the male is more easily suppressed than that of PI. 1.