The mechanism of acupuncture anesthesia has been investigated with rabbits. Points Shen--Su and Tsu--San--Li are needled. The chief results are summarized as follows: 1. It is proved that the mechanism of acupuncture anesthesia is determined by some internal factors, having a materialistic basis. 2. With 87 rabbits, 209 laporatomies have been performed. Some rabbits receive 4 operations, the resting period between two consecutive operations on the same animal being over one month. Comparing the alternative results of acupuncture anesthesia and no anesthesia (blank control) that have been observed from different as well as the same rabbits, we find that acupuncture anesthesia under suitable conditions is really effective. Anti--pain effect has been obtained in 48 out of 100 cases. Rabbit has been proved to be a suitable animal model for the study of the nature of acupuncture anesthesia, i. e. for the exploration of the action of chemical agents existing within the body to perform the functions of regulation, anti--pain and protection against wound. 3. With the blister technique, the research group and staff members tested on themselves the action of two neurotransmitters, including noradrenaline and acetylcholine, as well as two hormones, including adrenaline and pituitrin. They found that all these agents produce pain, but under certain mode of application or dose variation, they can be converted to antagonize the pain produced by histamine in cases of noradrenaline, adrenaline and pituitrin or become painless in case of acetylcholine. 4. Utilizing the fact that these neurotransmitters and hormones are antagonistic to B. P. but synergistic to anti -pain, a solution mixed in suitable proportions (NA 1 .pit 2 .5. Ach 0 .25) is infiltrated into the vein. It is found that the B.P. remains constant and the anesthetic effect is quite evident. Such procedure is temporarily called as humoral anesthesia. 5. When humoral anesthesia (NA 194--576 ug/ Kilo, Pit. 0.,49 -1. 44 Unit/ Kilo & Ach 24--72 ug/ Kilo) is given ahead of the acupuncture, the general efficiency is raised by 30% and the visceral traction effect is markedly controled. 6. Electromicroscopic studies of the adrenal gland reveal that in the medulla, during the induction period, under the influence of the liberation of acetylcholine in the synaptic region of the nerve endings, the release of the eatecholamine granules increases. Similar changes are shown in the cortex. Furthermore, in corticomedullary cells, following the release of catecholamine granules, the contents of liposome tend to decrease and empty spaces become enlarge correspondingly, indicating the possible release of cortical steroids. The activity of the macrophages in the medulla is much enhanced. These are assumed to be the cytological basis of the functions of anti--pain and protection against wound. 7. The induction period in acupuncture anesthesia is of extreme importance. No operation can be done without it. After 30 minutes of induction, operation can be performed smoothly for hours, even if the needles on the points are pulled out, when no stimulation is given further. In view of the physiological and cytological findings stated above, as well as the fact that the functional connection between Tsu--San--Li and the vagus having been known, it is postulated that. in the induction period, the sympatho--adrenal system and the vagus--postpituitary reflex are mobilized to release the neurotransmitters and hormones concerned in the functions of regulation, anti--pain and protection against wound. 8. The regulation of the antagonistic and synergistic actions of the neurotransmitters and hormones and their mutual correlations are extremely complicated. In order to map out the composite mode of actions of the elaborate internal changes, it is necessary to study in succession the other chemical agents in the body, such as certain amines, peptides, amino--acids, enzymes etc. 9. The “Meridian--cerebral cortex--viscera inter--correlation” hypothesis which explains the acupuncture effect from the view o The mechanism of acupuncture anesthesia has been investigated with rabbits. Points Shen - Su and Tsu - San - Li are needled. The chief results are rounded as follows: 1. It is proved that the mechanism of acupuncture anesthesia is determined by some Some rabbits receive 4 operations, the resting period between two consecutive operations on the same animal being over one month. Comparing the alternative results of acupuncture anesthesia and no anesthesia (blank control) that have been observed from different as well the same rabbits, we find that acupuncture anesthesia under suitable conditions is really effective. Anti - pain effect has been obtained in 48 out of 100 cases. to be a suitable animal model for the study of the nature of acupuncture anesthesia, ie for the exploration of the action of chemical agents existing within the body to perform the f unctions of regulation, anti-pain and protection against wound. 3. With the blister technique, the research group and staff members tested on themselves the action of two neurotransmitters, including noradrenaline and acetylcholine, as well as two hormones, including adrenaline and pituitrin They found that all these agents produce pain, but under certain mode of application or dose variation, they can be converted to antagonize the pain produced by histamine in cases of noradrenaline, adrenaline and pituitrin or become painless in case of acetylcholine. 4. Utilizing the fact that these neurotransmitters and hormones are antagonistic to BP but synergistic to anti-stain, a solution mixed in suitable proportions (NA 1 .pit 2 .5. Ach 0 .25) is infiltrated into the vein. It is found that the BP remains constant and the anesthetic effect is quite evident. This procedure is temporarily called as humoral anesthesia. 5. When humoral anesthesia (NA 194-576 ug / Kilo, Pit. 0. 49-1. 44Unit / Kilo & Ach 24--72 ug / Kilo) is given ahead of the acupuncture, the general efficiency is raised by 30% and the visceral traction effect is markedly controled. 6. Electromicroscopic studies of the adrenal gland reveal that in the medulla , during the induction period, under the influence of the liberation of acetylcholine in the synaptic region of the nerve endings, the release of the eatecholamine granules increases. Similar changes are shown in the cortex. Furthermore, in corticomedullary cells, following the release of catecholamine granules, the contents of liposome tend to decrease and empty spaces become enlarge correspondingly, indicating the possible release of cortical steroids. The activity of the macrophages in the medulla is much enhanced. These are assumed to be the cytological basis of the functions of anti- -pain and protection against wound. 7. The induction period in acupuncture anesthesia is of extreme importance. No operation can be done without it. After 30 mi nutes of induction, operation can be smoothly for hours, even if the needles on the points are pulled out, when no stimulation is given further. between Tsu - San - Li and the vagus having been known, it is postulated that. in the induction period, the sympatho - adrenal system and the vagus - postpituitary reflex are mobilized to release the neurotransmitters and hormones concerned in the functions of regulation, anti - pain and protection against wound. 8. The regulation of the antagonistic and synergistic actions of the neurotransmitters and hormones and their mutual correlations are extremely complicated. In order to map out the composite mode of actions of the elaborate internal changes , it is necessary to study in succession the other chemical agents in the body, such as certain amines, peptides, amino - acids, enzymes etc. 9. “The Meridian - cerebral cortex - viscera inter - correlation ”hypothesis which explains the acupuncture effect from the view o