"With the aforesaid laws, derived more immediately from malformations, a mistaken attempt has been made to couple two other special laws:

1. The first being that of Serres, according to whom the development of an organ altogether depends upon the development of the bloodvessels, and especially of the arteries. Conformably herewith, imperfect development, or the absence, or again the excess of an organ or part, would be a consequence of the insufficiency, or the absence, or again of the preternatural development of the supplying artery. But even were the fact altogether true, the cause of the defective or excessive development of the artery would still remain to be accounted for. The relation, therefore, not of dependence, but merely of correspondence between the degree of development of the malformed organ and of its supplying vessels, would be proved, as the rule, and even this subject to occasional exceptions. Bischoff, however, regards as decisive the direct observation that, in their rudiments, organs are immediately evolved out of the germ, previously to their being furnished from bloodvessels; the constituting cells subsequently becoming metamorphosed in such wise, that, out of one portion bloodvessels and blood, out of another the other (secondary) elements of the organ are derived.

2. According to the second law, the nerves are substituted for the bloodvessels, as the media of development. Tiedemann has shown that, with the absence of certain nerves is coupled the absence of their dependent organs; that in all monstrosities with excess, a corresponding relation is demonstrable in the nervous system; and, again, that in malformations with coalition of organs, the fashion of this union is exactly imitated by the supporting nerves. On the other hand, the natural history of development has shown that the central parts of the nervous system constitute the first vestiges of the embryo, being thrown oftt cognizably as such by the germ. Upon such grounds, the opinion has been formed that, like the normal, so also the anomalous development of the different organs of the embryo is dependent upon the normal or anomalous development of the nervous system. Against this view the objection hinted at in the last paragraph might again apply.

XVIII. The Disposition To Different Diseases Varies According To Age, Sex, Climate, Etc

Thus, aneurism belongs chiefly to manhood and advanced age, rickets exclusively to childhood; the foetus labors under anomalies proper to primary development alone - namely, malformations. In childhood tuberculosis attacks, preferably to all other parts, the lymphatic glands, the brain; at and beyond the age of puberty, the lungs. The female sex greatly favors the occurrence, in the sexual system, of cystoids, of cystosarcoma, of the majority of carfcerous growths. Under certain climatic relations, tuberculosis is rare, - intermittent fever, hypertrophy of the spleen, frequent; under the tropics the ossification of arteries is said to be extremely rare. Again, particular regions and parts of the body manifest different dispositions with respect to the frequency of congenital or acquired anomalies. Thus, Portal pronounces apoplexy to be more frequent in the right corpus striatum than in the left, - pneumonia is more common in the right lung than in the left. The arteries of the inferior extremities are infinitely more obnoxious than those of the superior to ossification and to spontaneous aneurism; the veins of the lower half of the body are almost exclusively subject to varix. Malformation from excess appears more frequent in the upper half of the body, malformation from coalition more frequent in the lower half; variations in the course of bloodvessels are more rare in the inferior extremities than in the superior.