PREFACE TO THE FIRST EDITION.
Pathologic Histology deals with departures from the normal in the various tissues of the body, which, occurring as the sequelæ of disease-processes, or standing in the closest causal relationship to the clinical symptoms and physical signs, constitute the foundation of all diagnostic conclusions, and of all rational therapeutic treatment. Without a definite knowledge of these abnormal changes, of their various forms, of the manner in which they arise and progress, no physician can deal intelligently with disease. The knowledge of the natural history of disease, based upon a knowledge of the normal body, makes the wise and successful practitioner; and to such, the autopsy, the microtome and the microscope must ever stand as constant aids in the satisfying of his intellectual curiosity.
It is, therefore, essential that the student in his undergraduate work should be so trained that, in addition to a broad conception of General Pathology, he may acquire also such a technical knowledge as to fit him to carry on his investigations after leaving the laboratory. Not only in everyday practice in certain lines is a knowledge of this technique necessary for diagnostic purposes, but the true physician should so hold himself toward every problem of diagnosis which presents itself to him, that with every opportunity, he will, through excision, curettage or autopsy, make use of his technical skill to further his knowledge of disease, and to aid his science toward a solution of its great problems.
It is for these reasons, that in my laboratory courses in pathologic histology, I wish to give each student a practical working knowledge of the technique of pathologic investigations. That the student become an expert as the result of such undergraduate courses is neither possible nor desirable; it is only hoped that he may be placed in a position to cope intelligently with the questions awaiting him in the field of practice.
For the guidance of the student toward this end, I have compiled this little book of laboratory methods, endeavoring to make it as practical as possible, but yet thorough and complete. The methods given are taken from the original papers, or from the compilations of Friedländer and von Kahlden, but are modified in many instances according to the writer’s own experience. The autopsy methods are, in the main, those used by Kolisko of Vienna; but methods of Virchow, Chiari, Nauwerck, and others, are also given.
It is from the study of the material itself, and not from the textbook alone, that the student can obtain a proper knowledge of pathologic changes. The most comprehensive textbook can give no adequate idea of the infinite variety of these changes; there is no absolute type, but an endless variety of appearances more or less closely related. Only from a contemplation of this variety is it possible for the student to build up a point-of-view, and to arrive at an independent and unbiased conclusion.
The student who seeks in a preparation only the appearances described in a textbook is not studying in a scientific way. He will constantly accept the author, instead of using his own impressions for the basis of deductions, guided by the experience of others. With an unbiased mind the student should take each specimen for that alone, which it, itself, presents; and upon this he should build his conclusions. He should seek in the textbook the things he finds in the material; not seek in the latter the things he reads in the former. Thus may he escape superficiality, avoid errors and hasty judgments, and build up for himself a sure foundation of knowledge. For these reasons the students in my laboratory course, having been thoroughly prepared for such work by the study of normal tissues in the histologic laboratory, are given the pathologic material as unknowns, which under careful guidance, they are enabled to work out for themselves to a satisfactory conclusion.
The student is further aided in the fixing of his impressions, and in their expression, by means of the drawings and written descriptions which he is required to make of the preparations. In this way the faculties of observation and expression receive a training that is not otherwise possible. It is true that such a course of instruction is difficult for the student whose previous training has been deficient in the cultivation of these most important faculties; for this reason it is the more necessary that he should now apply himself to work in the scientific method.
That this method of teaching takes much more of the instructor’s time is true; that it takes too much time cannot be granted when measured according to the results obtained. The frequent objection of the student that he cannot draw only emphasizes the necessity of that student’s receiving the necessary training to enable him to reproduce his visual impressions.
A greater difficulty lies with the teacher. Not only must he select his preparations with wisdom, so that in the necessarily limited time of the course, the student may receive the greatest benefit; but he must be tactful and patient in leading the student to work for himself. It is easy to give a demonstration and then tell the student to work; it is very much more difficult and nerve-consuming to make the student see and demonstrate for himself. The relation of the microscopic preparation to the gross anatomy must be shown, and, when possible, demonstrated by macroscopic preparations; further, the relation to the clinical symptoms and physical signs must be made clear, so that the student receive not a narrow conception of pathologic histology as something in itself separate and complete, but as a foundation-stone to the broadest conception of diagnosis, whereby the real unity of his studies will be revealed. Moreover, the teacher must be fully awake to individual differences and needs, and carefully shape his teaching influence upon each student accordingly. The problem of the individual equation becomes especially difficult in a course of this kind.
The laboratory course in histologic pathology, in the University of Michigan, follows the general order given in the second part of this book, beginning with the diseases of the blood and the circulation, and finishing with the special pathology of the most important organs. A preparatory training in general technique is first given. About one hundred and seventy-five prepared specimens, each illustrating some especial pathologic point, are given to the class as unknowns for diagnosis. In addition each student is required to prepare about fifty slides from fresh material, performing for himself all of the necessary technical manipulations, according to the methods given in this manual. To further the work in this course, and to meet the needs of advanced students and of practitioners, this book is primarily intended.
Aldred S. Warthin, Ph.D., M.D.
Ann Arbor, January, 1897.