Girls have a physiological reaction after the vagina out of the transparent color liquid, it is neither water, nor leukorrhea, but the Bach’s gland fluid, also known as “love juice”, “Yin liquid”. Love juice is in girls have physiological reaction, sexual excitement, from the vaginal wall and next to the vestibular glands, cervical glands and other glands will increase the secretion, containing a lot of water and mucus, mainly in the sex play a lubricating effect, but also has the role of protecting the sperm. It can ensure the survival rate of sperm and prolong its survival time on the basis of neutralizing the acidity in the vagina, protecting conception.