Such a case of rachitical cranial sclerosis I have described in the _Amer. Med. Monthly_ of 1861. It was, however, by no means a mate of the case related by E. Huschke. The latter skull was that of a girl of seventeen years, and weighed 4117 grammes instead of the normal weight of 600 grammes. The medullary (Havers') canaliculi were large and very numerous on the surface, narrow and very few in the interior of the sclerotic bones, and the osseous canaliculi were more spherical and irregular in site and shape. The chemical composition was also abnormal, phosphate of lime being 65.59, carbonate of lime 11.12, sulphate of magnesia 1.14, cartilage and fat (very little), etc. 22.15 per cent. No fluorate of lime was found. Most of the bones were exceedingly hard, but fragile when tried in small pieces; very white inside, yellowish on the surface, the latter color being the remnant of extravasated blood or other pigmentous matter. Another skull, in Huschke's possession, and moderately sclerotic, weighed (lower jaw excluded) 1075 grammes; a third, in the museum of the University of Jena, is that of a young baboon,[14] in which all the bones covering the hemispheres had become sclerotic. [Footnote 14: Baboons suffer from rachitis very extensively. In the _Transactions of the Pathological Society of London_ (xxxiv., 1883, pp. 310, 312) I. B. Sutton gives the description of two baboons, one of which was six months, the other one year and six months old, when they died. The careful description of the specimens exhibited leaves no doubt as to the rachitical nature of the changes in both the periosteum and the tissue of all the bones of the body.] Of undoubted total cranio-sclerosis Huschke reports but ten cases--those of Malpighi (1697), Cuvier (1822), Ribalt (1828), J. Forster and Bojanus (1826), Ilg (1822), Kilian (1822), Otto (1822), Vrolik (1848), Albers (1851), Huschke (1858). The disease does not affect the auditory bones, the condyles of the maxillary and occipital bones, nor the styloid process of the temporal bone. It is recognizable in the posterior part of the cranium and basis cranii, but affects mostly the bones of the face and the frontal, parietal, and cribroid bones. Thus, the disease takes its origin in the anterior portion of the skull, particularly in the superior maxilla, and proceeds upward and backward, terminating in the basis cranii in the neighborhood of the infundibulum and appendices. But two of all the cases were observed during life. In all the disease was traced back to early life. The chemical composition of the bones was greatly changed in all. Instead of the normal proportion of earthy to organic material = 2.1 (or 1.5):1, it was from 3.5 to 4.4:1. Particularly the carbonate of lime was greatly increased.