The cases in which the source is mainly central, rather than peripheral, nevertheless merge into the foregoing, with no clear line of demarcation. In such cases a girl forms an ardent attachment for another girl, probably somewhat older than herself, often a schoolfellow, sometimes her schoolmistress, upon whom she will lavish an astonishing amount of affection and devotion. There may or not be any return; usually the return consists of a gracious acceptance of the affectionate services. The girl who expends this wealth of devotion is surcharged with emotion, but she is often unconscious or ignorant of the sexual impulse, and she seeks for no form of sexual satisfaction. Kissing and the privilege of sleeping with the friend are, however, sought, and at such times it often happens that even the comparatively unresponsive friend feels more or less definite sexual emotion (pudendal turgescence, with secretion of mucus and involuntary twitching of the neighboring muscles), though little or no attention may be paid to this phenomenon, and in the common ignorance of girls concerning sex matters it may not be understood. In some cases there is an attempt, either instinctive or intentional, to develop the sexual feeling by close embraces and kissing. This rudimentary kind of homosexual relationship is, I believe, more common among girls than among boys, and for this there are several reasons: (1) a boy more often has some acquaintance with sexual phenomena, and would frequently regard such a relationship as unmanly; (2) the girl has a stronger need of affection and self-devotion to another person than a boy has; (3) she has not, under our existing social conditions which compel young women to hold the opposite sex at arm's length, the same opportunities of finding an outlet for her sexual emotions; while (4) conventional propriety recognizes a considerable degree of physical intimacy between girls, thus at once encouraging and cloaking the manifestations of homosexuality.