Salamander Tolerance of Acidity 
43 
Fig. 1. Volume of spotted salamander egg masses as a percentage of the 
original volume. The dotted line indicates no change. 
irregular egg masses from the study because these may not be 
representative of normal, single reproductive attempts. As a result, our 
experiments were performed using egg masses that were rather uniform. 
Although large egg masses may have a beneficial effect on larvae deep 
within the mass by providing local buffering, we observed that mortality 
was largely a matter of death of most eggs within single masses. Pough 
(1976) noted that the buffering capacity of the gelatinous matrix of 
ambystomatid egg masses was slight, but found that the few surviving 
embryos in acid waters tended to be in the centers of masses. Evolution 
of acid tolerance may take the form of natural selection of larger egg 
masses, and this hypothesis deserves consideration. Second, hatching 
success varies because temporary pools differ greatly in chemical 
