Od. 4, 1877] 



NA TURE 



483 



Another thought which occurred to me in the course of 

 my labours, and which I expressed in those earhest 

 records of them, has relation to the force by which the 

 poisons of the various diseases are developed and thrown 

 off. It is well known that the production of the poisons 

 in a living body infected by one of them is limited in 

 respect to duration of time of production even when the 

 body lives and recovers. This fact seemed to me to 

 prove to demonstration that the poison itself is produced 

 by the affected body, and is determined in its production 

 by some natural function of the body or of some part of 

 it. On the basis of my theory, that the poison in every 

 case is a modified secretion, this view of the force of pro- 

 duction of the secretion is easily accepted as in accord- 

 ance with natural law. The force of production is the 

 force of secretion, and so long as the secretion continues 

 changed in character, so long it is thrown off as a 

 poisonous secretion. But so soon as the modification of 

 secretion which rendered it poisonous is stopped, so soon 

 the secretion, flowing onward as before, is rendered 

 innocuous, that is to say, no longer poisonous. If this 

 were not the case, there is no reason, as far as I could 

 see, why, in every instance of infection the infected 

 person should not die. Endow the poison itself with 

 independent forces of life and of reproduction, give to it 

 a distinct reproductive life of its own ; then why should it 

 ever cease to reproduce.' Why should it not in every case 

 continue to increase within the infected body indefinitely 

 until it kills the body, and why should any one ever 

 recover .' But consider the poison as a part only of the 

 animal body itself, a substance to be eliminated from the 

 body by natural methods and then the process of removal 

 of the poisonous condition comes into the natural course 

 of events, and recovery is a natural process, unless 

 some unusual conditions occur to interrupt the natural 

 course. 



We see in a common nasal catarrh the outline of 

 this scheme. There is first a dryness of the secret- 

 ing surface, with refle.\ nervous irritation and much 

 nervous depression and disturbance thereupon in the 

 circulation of the blood. After a time there is a 

 copious secretion from the nostrils, which continues 

 until the disturbed nervous balance is brought back 

 to steady natural action. At that time the excess of 

 secretion is checked, and nothing more is left than the 

 local effects of hardened secretion or scale due to 

 the desquamation caused by the excessive previous 

 action. In outline this is really the natural course of 

 every epidemic disease, with the exception that the secre- 

 tion of a catarrh is not definitely proved to be a conta- 

 gious secretion. I believe it may be so, and sometimes 

 is so ; but I need not press the point. The illustration is 

 adduced merely to show that the course of the disease is 

 from within outwards, and that it is checked in its course 

 by restoration of internal natural function. If catarrh 

 were produced by some external vital agency, reproduc- 

 tive in character, fighting upon the nasal tract ; if it were 

 due to the colonisation of the nasal tract by an army of 

 foreign invaders which settled there and began and con- 

 tinued to replenish and multiply, when would the catarrh 

 cease? It would, as far as I can see, continue, until by 

 destruction of parts and continued abstraction of secre- 

 tion and extension of mischief over a wider tract of sur- 

 face, it killed inevitably. 



A catarrh, according to my view, as it was originally 

 expressed, is typical of all the diseases which run 

 a given course, and are called spreading diseases. It 

 springs up constantly from external atmospheric varia- 

 tions ; it runs a given course ; it subsides. It is an 

 epidemic, and it would be a true contagious epidemic 

 if the matter secreted from the nasal cavity and the 

 conjunctiva were not so innocuous. As I have hinted 

 already, I believe it may be contagious. I am quite 

 sure that many times in my life I have taken catarrh 



by coming" near to a person who was affected by it, but 

 whether this contagion is sympathetic or toxic, I am 

 not able to define. On these intimate relations I shall 

 have more to say on a future page. 



The Germ Theory. 



In the ten years that have passed since the time named, 

 another hypothesis in reference to the spreading diseases 

 and in relation to their origin from particular poisons has 

 been brought prominently forward. Owing chiefly to the 

 simple name which has been given to this hypothesis, 

 and the commonness of the analogies on which it is based, 

 it has gained much popular favour — I 'need hardly say 

 that I refer to the so-called germ theory of disease. 



This hypothesis has been most prominent for eight or ten 

 years, but it is really a very old speculation indeed, perhaps 

 one of the oldest in medicine. It has its root in the fancy of 

 the analogy that as seed cast on the ground yields, or may 

 yield, a certain harvest after its kind, as a field or garden 

 plot may become fertihsed by vegetable seeds or germs 

 which may come to it borne by the atmosphere or by 

 other modes of conveyance, so the body may be infected 

 with germs of disease, which germs, being received in the 

 body as a field for their reception, may increase and 

 multiply in the body, and by their presence excite the 

 phenomena which particularise all the special diseases of 

 a communicable kind. 



In modern times Dr. Grove, late of Wandsworth, was 

 the first to advocate this hypothesis, and I need not tell 

 a learned assembly like the present tint it has been most 

 energetically advocated more recently by many of the 

 ablest foreign and English men of science. In the 

 course of the discussions and of the researches which 

 have been conducted on this subject much knowledge 

 has, I am sure, been gained in the domam of natural 

 history, and much interesting discussion for history has 

 been written on the origin of some forms of life. But I 

 protest that the attempt to connect this knowledge with 

 the phenomena of the various communicable diseases, so 

 as to suggest, or, as some do, to assert, that the diseases 

 in question arise from germs, and that the person 

 afiected with a contagious disease has been fertilised 

 like a piece of ploughed land or virgin soil by a crop 

 of germs, and that in turn he is the soil in which 

 another crop is being produced by the independent in- 

 creasing and multiplying of the germs in him, I protest, 

 I say, that this hypothesis is the wildest, the most 

 innocent, the most distant from the phenomena it 

 attempts to explain, that ever entered the mind of man to 

 conceive. What most astounds me is that men who are 

 conversant with the practice of physic, who are treating 

 diseases of a communicable kind every day, should for a 

 moment connect such a hypothesis with the phenomena 

 they have under their observation. Does any one of them 

 believe that hydrophobia is from a germ, that syphilis is 

 from a germ, or other diseases I need not specify ? 



It is suggested by some advocates of the germ speculation 

 that the cause of the communicable diseases is after the 

 manner of the putrefaction of dead organic matter. Does 

 any physician who thinks as he observes, see anything 

 like a general rule of putrefactive change in the contagious 

 diseases ? He may of course see local decompositions of 

 secretions and of blood itself in the course of any of the 

 diseases, but these he knows are all secondary results, 

 while he may see and constantly does see all the diseases 

 running their course without any sign whatever of the 

 kind. Nay, in regard to one disease — cholera — he may, 

 as I have done, see it run its fatal course and leave the 

 dead bodies as loth to decompose as if they had been 

 embalmed. Again, does any physician, who thinks as he 

 observes, fail to see that the first symptoms of every one 

 of the contagious diseases ai'e purely nervous symptoms, 

 that they indicate nervous irritation, and that the par- 

 ticular local injuries which occur are not primary at all, 



