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The body wall of the cercaria of Schistosoma japonicum is covered with a thin integument which is connected to epithel cells located under the uscle layer. On the outer and the basal surfaces of the integument are seen thin limiting membranes. In the matrix of the integument are distributed numerous dense granules, vacuoles and spines. The rootlet of the spine is attached to the basement membrane of the integument. The circular and longitudinal muscle layers, both underlying the integument, have smooth muscle fibers composed of thick and thin myofilaments. The cercaria possesses five pairs of secretion gland cells which are divided into two groups of three anterior and two posterior pairs. Both gland cells are filled with secretion balls. The tail of cercaria is likewise covered with a thin integumen t, whose structure is identically the same as the body integument. Beneath the integument are located thin circular and longitudinal muscle layers. The circular muscle cells have smooth muscle fibers, but the longitudinal muscle cells have striated muscle fibers. These muscle cells contain many large mitochondria. On observing the cross-sections of the tail at the flame cell level the arrangement of these muscle can be divided into four muscle groups and each muscle group reveals four or five muscle cells. The excretory system is well developed and has flame cells, excretory canal and bladder.

The present study was undertaken to determine whether a biventricular bypass system operated in an independent variable rate (VR) mode can maintain the entire circulation. Two pusher-plate pumps which incorporated the Hall effect position sensors were used to bypass the right and left ventricles in 10 sheep under fibrillation. The flow distributions of the pump output to the carotid and renal arteries were investigated every 6 h using ultrasonic blood flow meters for 24 h in 5 animals, and the controllability of the VR mode was evaluated in 5 long-term experiments. The carotid artery flow ratio to the pump output decreased significantly from 4.7 +/- 0.8% before the bypass to 2.7 +/- 0.9% after 24 h. However, the renal artery flow ratio did not change throughout the experiments. In the long-term experiments, the animals were kept alive from 3 to 48 days (mean 15.6 days). The mean pump output had been maintained at more than 90 ml/min/kg for the first 7 days. After the surgery, the pump driving conditions were not readjusted in any experiment. The results indicate that the biventricular bypass system operated in the independent VR mode automatically maintains the entire circulation at a satisfactory level.