NEPHRITIS A rational classification of the various types of nephritis should be based upon its etiology ikriedrich Muller,* Bootlick). This method of considering Bright's disease is certainly: desirable in infancy. since. because of its dependence upon particular infections and intoxications, frequent at this age, the disease will in most cases exhibit a tolerably characteristic urinary analysis. But it is necessary,' to emphasize the fact that a complete etiological classification is not yet possible because the etiology of the so-called chronic parenchymatous nephritis is often obscure, its origin cryptogenetic, as in the case in adults.
It is therefore necessary still to cling, at least in the main part, to the division of chronic diseases which has come down to us from Wagner, and which has been adopted by IIeubner.
In reference to the postulate of Ponfick, and in order to provide a classification in which the etiology' and clinical anatomy are as closely related as possible, we shall separate the discussion of the nephritis of infants from that of older children. In this way the etiological impor
tance of previous disease will be recognized at least in part. Thus in older children the development of Bright's disease is pre-eminently influenced by the infectious diseases (especially scarlet fever and diphtheria), while in infancy the gastrodutestinal disorders are the predominant causal factor. Recent researches have taught us that the renal affections resulting from congenital syphilis form a group whose pathological anatomy is fairly distinct, and we are entitled to hope that the more perfect we make our exandnations and the more carefully we trace the causal factors, the smaller will be the number of cases whose eti ology we cannot explain. Meanwhile we are forced to be content with a classification which is perfect neither from the standpoint of etiology nor from that of pathological anatomy.