Physiology of Acclimation to Low Temperature in Poikilotherms.

Potassium, sodium, and calcium increase and chloride, magnesium, and free amino acids decrease in cold acclimated fresh-water mussels and earthworms. Increased protein synthesis occurs.Neurosecretory cells of cold earthworms exhibit increased activity. Addition of cold worm body fluid stimulates increased O(2) consumption by normal tissues, indicating that a hormonal agent triggers the sequence of changes.