1. The absorption and initial metabolism of glucose by the acanthocephalan Polymorphus minutus have been studied in vitro under conditions designed to approximate to those in vivo.
2. The results of the investigation of the absorption of glucose are compatible with the assumption that a carrier system is involved in the transport of glucose. The carrier system is half-saturated at an external glucose concentration of about 0.25 mg./ml. and is tending towards full saturation when the external glucose concentration reaches 2.0 mg./ml.
3. P. minutus has been shown to be capable of absorbing glucose against a concentration gradient.
4. The rate of glucose absorption, at a given glucose concentration, has been found to fall when the worms have been acclimatized to that concentration. It has been estimated that P. minutus requires about 4 µg. glucose/mg. wet weight of worm/hr. in vivo, assuming that the external glucose concentration is at least 2.0 mg./ml.
5. After 4hr. incubation with radioactive glucose the radioactive label has been detected in a variety of metabolites extracted from the worms. Evidence is presented indicating that these include: glucose, sugar phosphates, maltotriose, UDPG, glycogen, amino sugars, amino acids and organic acids.
6. Trehalose has not been detected in P. minutus, and a possible evolutionary significance of this result is discussed.