# Defensive Ferments of the Animal Organism/Preface to the First Edition

Preface to the First Edition.
In my text-book on Physiological Chemistry, published in 1906, I made an attempt to harmonize the defensive measures, adopted by the animal organism against products generated by cells out of harmony with the body, with the metabolic processes of the individual cells of the body. I was of the opinion that, when an invasion takes place of cells which are out of harmony with the body, the blood or plasma, and the cells, the cells of the body respond with counter-measures which are not entirely new to the cells of the particular organ or of the blood; on the contrary, I tried to bring the whole question of the so-called reactions of immunity into close line with processes that are normal, and consequently familiar, to the cells. From the point of view stated in the above-mentioned text-book, I attacked experimentally the problem of the method of defence, used by the animal organism, against the invasion of substances out of harmony with the body, the blood plasma, and the cells. In the first place I studied the question whether normal blood plasma contains definite ferments; and, in the second place, whether the introduction of disharmonious substances is followed by the appearance of ferments which were not there before. I found, in fact, that, after the ​introduction of substances out of harmony with the blood plasma, ferments appeared which are capable of transforming these products, and of depriving them thus of their specific character. These facts established beyond doubt one means of defence possessed by the animal organism against the invasion of disharmonious substances.
My thoughts then turned at once to the relation of these facts to immunity, and especially also to anaphylaxy, and I undertook experiments to decide the question as to whether the animal organism develops any ferments of a specific nature against substances produced by micro-organisms. And I was particularly interested in the question whether the stages that arise, in any given case, during the decomposition of a particular substrate vary with the species of the invading cell, and whether this may not give us the explanation of many phenomena that appear in the course of certain infections. Finally, I was able to demonstrate that, during pregnancy also, the organism defends itself, by means of ferments, against certain constituents which are passed into the blood, most probably from the cells of the chorionic villi, and which, though in harmony with the species, are out of harmony with the plasma. This observation renders possible a diagnosis of pregnancy.
The above statements have a bearing on a great ​number of particular problems connected with immunity, which still await solution; nor is there any doubt that many well-ascertained facts are closely connected with the results of our researches. Even now it would be tempting to select suitable instances from the mass of my particular observations, with a view to giving a more general signification to the views I have formulated on the means of defence possessed by the organism against the invasion of substances or cells that are out of harmony with the body. For the time being I have refrained from doing so, as the mere enumeration of closely related observations, quite apart from a discussion of all the hypotheses put forward, would enormously increase the scope of this little volume, and incidentally would interfere with a clear insight into our subject.
Again, it is very difficult, for those not actually engaged in research work on immunity, to keep in touch with all the communications made at different times concerning ideas and theories that are constantly changing, and above all to find a sure footing amongst the somewhat pleonastic terminology and nomenclature employed. Theory and actual fact form, in this field of research, a closely interwoven net of conceptions; so much so, that only those, who have already acquired, by actual corroboration, a thorough knowledge of all the problems connected with the subject, are able to trace sharp limits ​between hypotheses and facts. For these reasons I have limited myself to making mention of those works which either are closely connected with my own researches, or else will be of special service to the reader, in that the full lists of references they contain will be a guide to further study in this field of research. This limitation alone has enabled me to present a picture—which, I hope, is quite clear—of the development of my own investigations, and to show how I arrived at the doctrine of the active part played by ferments in connection with disharmonious substances.
The comprehensive survey, which I now present, has resulted from the fact that many problems have been so far advanced, recently, by means of experimental work, that it seemed advisable to take stock of the observations that lie stored in numerous publications. And, on the other hand, I find that the further study of particular problems can be carried on only in institutions supplying means and apparatus which I cannot command. One man by himself is able in certain problems to reach only a certain point. He takes over, as it were, an edifice which has been built up to a certain height from all possible sides. He tests the scaffolding—the existing working theories—to see whether it will last any longer, or whether it must be replaced; and, more important than that, decides ​whether the structure itself is perfectly sound. He then builds further, but in most cases makes only a tiny addition. It is very easy for a single observer to lose a clear view of the whole, through using too complicated a scaffolding. Others follow; they test the solidity of the structure, they move the misplaced bricks into their correct position, and give a finishing touch to the parts that are insufficiently trimmed. Each new workman brings new tools, new ideas, and his own extensive experience with him, and tackles the whole structure from different points of view. Then the scaffolding is removed, and a mighty building appears, which scarcely gives any idea how diverse were the plans on which it was founded. So, too, this contribution to our knowledge of the functions of the cells may be considered only as an attempt to adjust a new stone in the already existing structure, and to construct a scaffold from which further progress may be made.
In conclusion, may I be permitted to express my heartiest thanks to my collaborators, whose untiring energy has made it possible to accomplish so many single experiments in such a relatively short time, and to work out different problems from various standpoints at the same time.
Emil Abderhalden.
Halle a/S., April 15, 1912.
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