Those who put forward memory as the basis of heredity show that evolution implies the retention by organisms of their experiences in accommodating themselves to their gradually changing environment. Constant and reiterated striving in certain directions in this process of accommodation, until actions become automatic--free of effort--produces habit. In the words of Professor Ward: "This law of habit we may reasonably regard as exemplified in the life of every individual in the long line of genealogical ascent that connects us with our humblest ancestors, in so far as every permanent advance in the scale of life implies a basis of habit embodied in a structure which has been perfected by practice."[64] Laborious observations have been recorded of minute unicellular creatures to show that they "succeed as we do, only by way of trial and error." Thus we are led to the conclusion that the acquisition of habits by the individual during his efforts to adapt himself to his environment, and transmitted down a long line of genealogical descent, is the method of heredity; and further, that man, in common with other animals, inherits all these racial and individual acquirements from his parents. Instinct, we have said, may be termed the "Suggestion of Heredity," which again is "race memory," or the evolutionary product of habits acquired during the process of man's adaptability to his environment. This, then, is the primary and fundamental determinant of the character and quality of personality. It is the quality which is inherent in a man from the moment he begins his individual existence, that is, from the moment the sexual cells of both parents coalesce in the process of conception and form a new stem-cell. Haeckel divides the instincts into two chief classes: the primary, which can be traced to the commencement of organic life--the common lower impulses inherent in the psychoplasm. The chief are impulses to self-preservation (by defence and maintenance) and the preservation of the species (by generation and the care of the young). These two, hunger and reproduction, are universally recognized as fundamental. The secondary were due to intelligent adaption; translated into habit, they gradually become automatic and "innate" in subsequent generations. The earlier these habits are acquired and ingrained in the life history of the race, the more invariable and immutable will be their transmission; the habits of a few generations are easily modified or effaced by conflicting tendencies or conditions. The life history of every new individual, in its initial stages, is a (more or less complete[65]) recapitulation of the life history of the race. The _earlier_ ancestral acquisitions have been transformed into habit and have become secondarily automatic, the less are they liable to variation, and the more inexorable and unfailing will be their transmission. Thus Darwin showed the greater immutability of generic characters over later