Abstract: During May. 1992, the breeding season of Myospalax, eighteen female Myospalax were caught in three habitats at Jingzhong towns, Zhang county, Gansu Province. After anatomy, a foreign body as sarcoma belonging to parasitic bladder and fibroma was discovered in the vagina. It inhibited the gestational rate (only 33.3%) and the number in every fetus (x=2) of Myospalax population and limited to increase of number of Myospalax population. The further investigation confined that the density of Myospalax population had been declined. The mechanism of the natural regulation was analyzed as follows: Under condition with enough food, when the density of Myospalax population reached the highest limit, the individual number of the host animal of catching parasitic and the infections rate increased. The parasitic that controled Myospalax breeding invade the vagina, decreased the density of Myospalax population until the lower level. The parasitic and its life cycle need to be studied in the furture.

Key words: Lonicera japonica, cadmium, hormesis, hyperaccumulation.