BLOOD AND SPLENIC RESPIRATORY COMPENSATION IN LARVAL NEWTS

In Triturus carnifex, the mechanism of respiratory compensation which regulates the quantity of circulating erythrocytes according to the en vironmental conditions is already active in larvae at Glucksohn's stag e LXI. Larvae anesthetized with chlorbutol and kept at 27 degrees C fo r 25 min show red blood cell (RBC) counts slightly below 70 000/mm(3) and hematocrit values around 17, while those kept at 6 degrees C for 1 00 min - the time necessary for the heart to bear the same number of t imes as at the former temperature - show significantly lower values (P < 0.01): about 40 000 RBC/mm(3) and a hematocrit of Il. The percentag e mass and histology of the spleens removed from specimens frozen in l iquid nitrogen immediately after testing show that this organ is the s ite where excess erythrocytes are stored. Tests at 18 degrees C show t hat, though the voluntary movements of the anesthetized larvae are com pletely blocked, their gills still move rhythmically, which prevents t hem from going into hypoxia in stagnant water as, instead, occurs in a dults.