Alkaline Phosphatase in Protonephridia of Terrestrial

I . Application of the Gomori method to sections of the terrestrial nemertine Geonemertes dendyi shows that there is no alkaline phosphatase in the flame cells or in the distal glandular canal of the protonephridia. But the proximal ciliated convoluted canal and the branching ciliated terminal ducts are rich in this enzyme. 2. Sections of the terrestrial triclad Rhynchodemus terrestris show the presence in the parenchyma of numerous ciliated convoluted canals resembling those of the nemertine. 3. A study of the protonephridial system of R. terrestris shows that this consists of numerous Same cells connected by branching unciliated ducts with the phosphataserich ciliated convoluted canals. The latter connect with unciliated distal canals which probably connect with the numerous exit ducts. These exit ducts are apparently con>fined to the ventral surface, particularly along the ciliated creeping sole. 4. The convergence between these nemertine and turbellarian protonephridia, and their analogy with the differentiated tubule system of the vertebrate kidney, are noted.