laxity of the abdominal wall and the atony of the intestinal musculature, which is encountered so frequently in this disease, give rise to a tendency to the occurrence of umbilical herniEe. These hernhe usually remain small but they can, especially under the influence of an intercurrent whooping-cough, attain to the size of plums or even larger. Their prognosis is always favorable.
Complicating pulmonary diseases arise very easily with severe thoracic rachitis. Even a moderate bronchitis can be dangerous to life in this condition. A prognosis should therefore always be made with care. The worst feature is the fact that, in rachitis, catarrh has a dan gerous tendency to descend to the finer bronchioles, especially in poorly nourished individuals, and thus to lead to capillary bronchitis and bronchopneumonia. The prognosis for the last two diseases is always grave in rachitic children.
Diseases of the gastro-intestinal canal are frequent and serious complications. Especially to be feared are those catarrhal diseases of the large intestine which are accompanied with mucus stools. In the case of debilitated children the associated intestinal catarrh frequently becomes the specific cause of death.
The nervous complications are very important, especially spasm of the glottis, cclampsia and tetany. The importance of these spasms lies in the danger of sudden death in a laryngospastic or eclamptic attack. Sometimes nystagmus, rotatory spasm or spasmus nutans occur. The prognosis of these forms of spasm is good, and recovery almost always ensues after a few months of antirachitic treatment. The occasional occurrence of cataleptic conditions in poorly nourished raehitic children should be noted. The symptoms are those of the well marked " Flexibilitas cerea." Finally, the fact can hardly be disputed, that children with severe rachitis are more disposed than others to tuberculosis of the various organs.
Pathological to the severity of rachitis, the anatomical changes are of vastly different grades, from the very light. manifestations, whose differentiation from physiological states is diffi cult, to the severest lesions. In all cases except the mildest the rigidity of the bones is markedly impaired; occasionally this advances so far that one can bend the bones as if they were made of rubber. • At the same time there exists a considerable hypertemia of the periosteum and marrow. The periosteum is more or less, often very markedly, thick ened; the thickening being due almost entirely to an increase of the cambium layer. Directly under the fibrous layer are found uncalcified spicules of young bony tissue formed by ossification of the periosteum; between them lie the primary periosteal marrow spaces. In the deeper layers of the swollen cambium the new formed bony spicules are stronger, and the spaces between them arc narrower. The spicules which were first formed contain calcified fragments in their central portions but con sist otherwise almost entirely of uncalcified osteoid tissue. Further on one comes to the cortex proper into which open narrower vessel canals than the normal eanaliculi. The lamellue of the cortex everywhere show abnormally broad osteoid borders. Only in the places where the bony
tissue is undergoing absorption, which is especially apt to be of greater extent in the neighborhood of the central marrow cavity, does the cal cified bony tissue, which is well supplied with lacintar spaces, border directly upon the marrow tissue.
Fractures occur mDst easily at the time at which the new and pro portionately soft deposits form a fairly thick layer upon the deeper, compact, and relatively thin bony sheath which surrounds the central marrow cavity. The breaks in continuity occur for the most part only in the compact layer while the young superficial layers are compressed. Breaks occur usually only in the concave portions which lie in the angle of fracture, similar to the breaks which occur during the forcible bending of a willow twig (green-stick fracture), or a feather quill. The frag ments are displaced towards the convex side which narrows and often entirely closes the marrow canal; the marrow is accordingly pressed out and in part destroyed.
Gallus formation occurs in every place where the bone is fractured and usually, too, for a considerable distance about the break. Some times the entire angle of fracture is filled with callus which usually forces itself into the marrow cavity through the aperture of the fracture and thus leads to a complete closure of the cavity at this point. A tinuous marrow cavity is reformed only a very long time after tion. Rachitic callus bears a close resemblance to the young periosteal growth except that it far more frequently contains true cartilage. In the lightest cases the periosteal thickening affects only the edges of the cranial hones, but in the more severe ones the tuberosities also arc involved. The inner surface of the bones at all times remains free from rachitic deposits. The membranes which cover the sutures and fontanelles are lax, and thickened. The cranial bones are never all equally affected by rachitis; in typical cases the frontal bones are only slightly thickened at the edges, while the parietal bones are partly, and the occipital almost entirely, covered by a red spongy deposit. Very frequently there occurs at the same time in the region of the occiput a thinning of the bony plates which in severe cases amounts to the ap pearance of membranous gaps. Such a membranous area always cor responds with a digitate (Pacchionian) depression of the inner surface, while on the outer side its upper surface lies on the same level as the surrounding tissue. In all these cases of craniotabes, the other bones, especially frequently the ribs, show macroscopic rachitic changes, and with microscopic examination one never fails to find osteoid tissue in these craniotabetie areas. As to the remaining flat bones, the only point to be emphasized here is the fact that the pelvic bones very early undergo the well-known changes which are so important in obstetrics; but apparently in the pelvis as well as elsewhere the rachitic lesions are in many cases either completely or partially resolved in the course of further growth.