The correct proportion between chlorine, phosphorus, potassium, and sodium is certainly exhibited in woman's milk. There is lime enough in even the poorest article of that kind. But indigestion brought on by {155} woman's milk in a disordered condition or by any other cause will prevent the absorption of lime when a superabundance of phosphorus and potassium disturbs the formation of hydrochloric acid. In these cases not only the development of the bones, but also that of the muscles, is disturbed. The latter is of great importance in regard to circulation, because a large part of the circulation depends on the pressure on the part of the muscular fibres exerted on the small blood-vessels. These facts have been the reason why I insist upon the addition of chloride of sodium to the food of infants and children, particularly those who are fed on cow's milk; for cow's milk and vegetables contain a relative superabundance of potassium compared with sodium. Even adults will find cow's milk very much more digestible by adding table-salt to it. The extremities begin to suffer at a later period than the ribs and cranium. The opinion of Guérin, that the rachitical process begins in the lower extremities and ascends gradually, is erroneous. It cannot even be stated that the lower extremities are affected sooner than the upper. There is no regularity at all; it is not even necessary that all the osseous tissue should fall sick. But this can be taken as a fact, that hands and feet, and particularly the phalanges, are the latest to undergo the rachitical change. First in the line of morbid alteration of the bones are the epiphyses, mainly of the tibia, fibula, radius, and ulna. Their integument appears to be thin; now and then the cutaneous veins are dilated. The periosteum of the diaphysis becomes thick, softened, and painful to the touch and pressure, its compact layer thin, the medullary space large, the whole bone flexible, at the same time that the ligamentous apparatus of the joint becomes softened and flabby. At this time babies are greatly admired and applauded for the facility with which they introduce their feet into their mouths. For at the same time the bones begin to curve under the influence of the flexor muscles, which are always stronger, as they do in later months under the weight of the body when the child begins to walk. The curvature is not always a mere arching, but sometimes the result of infraction (green-stick fracture), a complete fracture not being accomplished because both of the softness of the osseous tissue and the resistance on the part of the thickened and softened periosteum. Both the legs and forearm bend on the external side, the resulting concavity looking inward. The humerus bends in a direction opposite to that of the forearm; the thigh, usually outward and forward.