The human heart may present in degenerates all types from the pulsating vessel found in the lancelet up to that of the mammal. The imperfect types of these sometimes perform their functions properly, except under strain. In other cases mixture of arterial and venous blood results, producing the so-called "blue babies." Under the teachings of the extreme disciples of Morel, it has been assumed that the family of the degenerate tends to irrevocable extinction. On the principle of individuation already outlined from Spencer, degeneracy, through its tendency to generalise rather than specialise function, causes too rapid development of cells which tend to extinguish each other, thus preventing proper ovulation; and, in the next place, the same condition prevents proper development of the ovum if formed and fecundated; and, finally, causes too numerous simultaneous developments of ova, which would tend to destroy each other. The same cause produces also premature extrusion of ova. At the same time, however, under given conditions, this principle also tends to produce reversions in type in the shape of too frequently repeated and abnormally multiple births. It has been noted that even the ancestors of those predisposed to phthisis have numerous families and many children at a birth albeit most of these die ere reaching the sixth year. Marandon de Monteyel[237] finds that multiple and frequently repeated pregnancies often occur among the families of hereditary lunatics. This has been corroborated by Kiernan[238] and Harriet C. B. Alexander,[239] of Chicago, in connection with the hereditary lunatics in Cook County. They found that 90 families of the hereditary insane averaged 11 children each. Six families had 5 children, 4 had 7 children, 8 had 8, 10 had 9, 14 had 10, 8 had 11, 4 had 12, 4 had 13, 4 had 14, 3 had 16, 3 had 17, 4 had 18, 3 had 19, 5 had 20, and 1 had 21 children, each. Twins, triplets, and quadruplets were six times as frequent as among normal families. Manning has found similar conditions among the hereditary insane in Australia. Valenta, of Vienna,[240] has noted this also among epileptics. He reports the case of an epileptic mother who had 36 children, including six twins, four times quadruplets, twice triplets. Her daughter, also an epileptic, bore 32 children before she was 40, including quadruplets twice, triplets four times, and twins once. Similar, though less striking, statistics occur with other classes of degenerates with proportionate frequency when the sterilising effect of certain diseases to which they are specially liable is taken into account. The general acceptance of the opinion as to large families being a test of advance in evolution seems strange when the extent and force of the action of the principle of individuation is taken into account, and when it is remembered how prolific are the lower vertebrates as compared with the higher.