The transition of blastospores to the mycelial phase in Candida albicans was induced after the blastospores were kept at 4 degrees C for several hours and then transferred to a fresh medium prewarmed at 37 degrees C. Glucan was the most abundant polymer in the wall in the two morphogenetic forms but the amount of chitin was higher in the mycelial form than in blastospores. Efficient protoplasting required reducing agents and proteases together with beta-glucanases (zymolyase). Protein synthesis in regenerating protoplasts was initiated after about 30 min. Chitin synthetase, initially very low, was incorporated in important amounts into cell membranes mainly in a zymogenic state. After a few hours chitin was the most abundant polymer found in the aberrant wall of the regenerating protoplast.