95 cases of chronic diarrhea due to we- akness of function of"Pi"（Spleen）were chosen for the study of the nature of"Pi" and treated by the principle of differentiat- ing symptoms and signs based on traditional Chinese medicine.Course of treatment va- ries from 2 to 3 months.Effective rate was 71.6%.Twenty and more items of exami- nations

including routine and biochemical examination of blood

feces and urine

im- munological function tests

barium meal

sig- moidoscopy and biopsy of the rectal mucosa etc.were performed.Seven prescriptions which are effective in treating diarrhea due to weakness of function of"Pi"were studied for their effects on the movements of an- imal duodenum in vitro.Based on the re- sult of clinical and experimental examina- tions and by reviewing the ancient and mo- dern literatures

the authors claim that the idea of"Pi"in traditional Chinese medicine doesn’t denote any concrete internal organ

but embraces a compound functional system

which includes the principal functions of the digestive system

and involves a certain func- tion of the vegetative nervous system

me- tabolism and immunity.