ALTERATIONS IN THE DIGESTIVE GLAND AND SHELL OF THE SNAIL HELIX-ASPERSA MULLER (GASTROPODA, PULMONATA) AFTER PROLONGED STARVATION

We investigated the effects of prolonged starvation on body weight and shell thickness, on the numbers of different types of cells, and on t he Mg/Ca ratio in the digestive gland and shell in the common garden s nail Helix aspersa Muller. A 60% reduction in body weight, which occur red after periods of starvation longer than 3 months, was critical for life. Starvation had a marked effect on the relative numbers of cells in the digestive gland, and significantly decreased the number of dig estive cells. The changes in Mg/Ca ratio in the digestive gland and sh ell were closely correlated. Changes in ion balance may have resulted from the need to compensate for the starvation-induced decline in extr acellular pH. The shell acted as a reservoir of ions that could be mob ilized under extreme conditions.