I. Chemical analysis A study was planned to see if administration of ginseng extract has any influence upon the adrenal, the hepatic, the splenic, and the pancreatic nucleic acid contents of rats, and to estimate the effect of ACTH administration as a substitute for stress reaction upon these nucleic acid contents of rats previously primed with ginseng. Ninety male rats(body weight: 150 ~ 200gm) were divided into the ginseng, the saline, and the normal control groups, which received for 5 days 0.5ml/100 gm body weight of ginseng extract solution (4 mg of ginseng alcohol extract in 1 ml of saline), same amount of saline, or no medication, respectively. On the 5th experimental day, each of the 3 groups was further divided into 2 subgroups yielding the ginseng, the ginseng-ACTIT, the saline, the saline-ACTH, the normal control, and the normal-ACTH subgroups. The ginseng, the saline, and the normal control subgroups were sacrificed 3 hours after the last medication, while the ginseng-ACTH, the saline¡¤ACTH, and the normal-ACTH subgroups received ACTH(0.1 unit/subject) 1 hour after the last medication and were sacrificed after 1 more hour. The adrenal gland, the liver, the spleen and the pancreas of each rat were measured for RNA and DNA contents using the chemical method of Schmidt-Thannhauser-Schneider. Following results were obtained: 1. Adrenal RNA and DNA contents and RNA/DNA ratio were all significantly higher in the ginseng group compared with the values obtained from the normal control and the saline groups. Generally administration of ACTH reduced nucleic acid contents of the viscera examined. However, in the ginseng group the rate of decrease [(value of ginseng-ACTH subgroup-value of ginseng subgroup) x100/value of ginseng subgroup)] in adrenal RNA and DNA contents and in RNA/DNA ratio were more conspicuous than they were in the normal control and the saline groups. 2. Hepatic RNA and DNA contents and RNA/DNA ratio were all significantly less in the ginseng group than in the normal control and the saline groups. After ACTH, the rate of decrease in hepatic RNA, DNA, and RNA/DNA ratio of the ginseng¡¤ group was less conspicuous than those of the other 2 groups. 3. With regard to the splenic nucleic acid contents, the RNA and the RNA/DNA values of the ginseng group were higher than those of the normal control group but lower than those of the saline group, while the DNA value of the ginseng group was lower than that of the normal control group but higher than that of the saline group. Following administration of ACTH, the rate of decrease in RNA and DNA contents and in RNA/DNA ratio of the ginseng group was more conspicuous than that of the normal control group but less remarkable than that of the saline group. 4. Pancreatic RNA and DNA contents were notably lower in the ginseng group than in the normal control and the saline groups. However, the RNA/DNA ratio of the ginseng group was higher than that of the normal control and the saline groups. After ACTH, the rate of decrease in pancreatic RNA and RNA/DNA ratio of the ginseng group was less than that of the normal. control group but more than that of the saline group, while the DNA content was actually increased in the ginseng group though it decreased in the normal control and the saline groups. Although the results are not clear enough for an accurate interpretation, they seem to indicate that ginseng exerts notable influence upon the RNA and DNA contents and the RNA/DNA ratio of the viscera stodied. On the whole the drug tends to increase the RNA and DNA contents and RNA/DNA ratio of the adrenal gland but seems to diminish the values of the other 3 viscera. In the early period following ACTH, ginseng facilitates the fall in RNA and DNA contents and RNA/DNA ratio of the adrenal gland, while it tends to reduce the fall in the values of the other viscera studied.