The practical point to be illustrated is the following: 

The disease known as Puerperal Fever is so far contagious as to be frequently carried from patient to patient by physicians and nurses.

Let me begin by throwing out certain incidental questions, which, without being absolutely essential, would render the subject more complicated, and by making such concessions and assumptions as may be fairly supposed to be without the pale of discussion.

1.  It is granted that all the forms of what is called puerperal fever may not be, and probably are not, equally contagious or infectious.  I do not enter into the distinctions which have been drawn by authors, because the facts do not appear to me sufficient to establish any absolute line of demarcation between such forms as may be propagated by contagion and those which are never so propagated.  This general result I shall only support by the authority of Dr. Ramsbotham, who gives, as the result of his experience, that the same symptoms belong to what he calls the infectious and the sporadic forms of the disease, and the opinion of Armstrong in his original Essay.  If others can show any such distinction, I leave it to them to do it.  But there are cases enough that show the prevalence of the disease among the patients of a single practitioner when it was in no degree epidemic, in the proper sense of the term.  I may refer to those of Mr. Roberton and of Dr. Peirson, hereafter to be cited, as examples.

2.  I shall not enter into any dispute about the particular mode of infection, whether it be by the atmosphere the physician carries about him into the sick-chamber, or by the direct application of the virus to the absorbing surfaces with which his hand comes in contact.  Many facts and opinions are in favor of each of these modes of transmission.  But it is obvious that in the majority of cases it must be impossible to decide by which of these channels the disease is conveyed, from the nature of the intercourse between the physician and the patient.

3.  It is not pretended that the contagion of puerperal fever must always be followed by the disease.  It is true of all contagious diseases, that they frequently spare those who appear to be fully submitted to their influence.  Even the vaccine virus, fresh from the subject, fails every day to produce its legitimate effect, though every precaution is taken to insure its action.  This is still more remarkably the case with scarlet fever and some other diseases.

4.  It is granted that the disease may be produced and variously modified by many causes besides contagion, and more especially by epidemic and endemic influences.  But this is not peculiar to the disease in question.  There is no doubt that small-pox is propagated to a great extent by contagion, yet it goes through the same periods of periodical increase and diminution which have been remarked in puerperal fever.  If the question is asked how we are to reconcile the