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early period after their development, it is frequently otherwise in 

 the case of essential fevers. These diseases are not so commonly 

 distinguishable at first sight. In order to collect the facts from 

 which their differential diagnosis may be deduced, it is often neces- 

 sary to observe them carefully, sometimes in more than single cases, 

 during the space of several successive days. Moreover in the phleg- 

 masia, the diagnostic phenomena are for the most part local, being 

 confined to the organs immediately affected. In fevers it is not so; 

 the diagnostic signs are spread throughout the economy, and are 

 slowly and successively developed, and not until a certain number 

 or variety of them have come fully into view, can a specific fever be 

 recognized. t 



Of the anatomical alterations produced by fevers, it may be said 

 that such of them as occur in the internal organs, and which are 

 discoverable only after death, have no absolute claim to the character 

 of diagnostic phenomena, since none of them are invariably present 

 in the same specific fever, and many of them are found in different 

 kinds of fever. There are, however, in some fevers, certain altera- 

 tions in the organism so frequently revealed by autopsic examinations, 

 that they may not improperly be admitted among the accessory 

 means of diagnosis, especially in cases in which neither the causes 

 nor the symptoms during life are sufficient to elucidate their dis- 

 tinctive nature. 



From these general observations, we proceed to the question of 

 the identity or non-identity of typhus and typhoid fever. And in 

 doing so, leaving out of view for the present the history of their 

 causes, we shall inquire: 



1st. Whether these diseases differ so much in their symptomatology 

 as to enable us to characterize them as distinct distempers? 



2dly. Whether the morbid anatomy, and particularly the intestinal 

 follicular lesions observed after death, indicate the diseases to be 

 specifically different ? 



1. Of the Symptomatology of Typhus and Typhoid Fever. — In 

 essential fevers there are a few symptoms which are common to 

 them all; and to these symptoms are added, in particular fevers, 

 certain phenomena which arise in the progress of the morbid move- 

 ments that mark their special form and character. Now among the 

 leading symptoms, mostly of the latter description, observable in 

 typhus and typhoid fever, are the following : great prostration of the 

 sensorial and muscular energies, cephalalgia, disagreeable dreams, 



