Backgrounds and ObjectivesBecause of the special structure of BBB, medicine and other xenobiotics can enter CNS depending on the presence of BBB and Blood-CSF as well as the physico-chemical properties. As the Olfactory system provides a direct pathway through inner brain to outer, the olfactory-to-brain pathway may be a new way for the CNS medicines' entry into the inner brain. Eugenol is one of the fragrance enlightened medicines,but its mechanisms of englightening has not been well studied.This research tries to approach the mechanisms of eugenol's influences on space learning and memory of animals though olfactory pathway.If Eugenol ,one of the fragrance enlightened medicine, can be administered through olfactory inspiratory way, then this pathway can be admitted as one of the most effective and simplest way for medicines' entry into CNS.This paper is to explore the mechanism of influences on learning and memory after Eugenol's administration through olfactory pathway. This paper can be divided into three parts:The first part:     The neuroethological observations on Kunming mice after Eugenol's administration through different pathways.Methods   To compare the different influences on Kunming mice after Eugenol's administration through different ways, three groups were slelected: Olfactory inhaling group; Nasal gutted group and Intragastric administration group. The changes of mice autonomic activities and learning and memory can be observed through neuroethology methods.