484 



NATURE 



{Oct. 4, 1 8; 



but nre dependent on srecial nervous change modifying 

 nutrition nt the part. Between a boil or abscess and a 

 pustule of small-pox what is the difference except in 

 degree of purulent matter formed at one point of forma- 

 tion of matter? 



There is nothing whatever in fact in the clinical history 

 of plagues that connects them with the hypothesis of an 

 origin from germs produced without the body and enter- 

 ing it to fertilise it and create a decomposition. When I 

 fay there is nothing, I mean there is nothing except the 

 analogy of which I have spoken above, and even that 

 breaks down, for the analogy of the fertilisation of a field 

 by seed means always a definite process of fructification 

 and of results from it ; whereas in the history of epidemic 

 plagues there is no such definition. 



The germ hypothesis fails, however, on other grounds 

 than the clinical. If it were true that living germs 

 possessing an independent growth and vitality enter the 

 animal body, that every disease of a communicable kind 

 is due to its own external living germ, and that the germs 

 continue to multiply and increase by an independent 

 action of their own ; if this be indeed true, why do the 

 germs after a certain time cease to multiply and allow 

 the sick person to recover ? Why do they not go on 

 multiplying until the person is infested in every pait and 

 fatally stricken ? Who would get well from a disease 

 due to living self-propagating contagions 1 Again, who, 

 if the hypothesis were true, would escape fertilisation ? 

 A general fertilising diffusion of self-propagating matter 

 in minute invisible form entering the body as the air may 

 enter could hardly be expected to select a small minority 

 of a population, and if it did so at the first, why should it 

 do so when it had seized upon many centres in which it 

 could increase. But the history of all the communicable 

 diseases shows that each epidemic affects individuals 

 individually at different periods in the course of the 

 epidemic according, as a rule, to exposure to the infected, 

 and that the period of the disease is limited by a 

 development and a course rendered in certain periods of 

 time. 



I need hardly add in objecting to this germ hypothesis, 

 because the fact is admitted, that not only has no one 

 ever seen a germ of disease, but that no one has ever 

 traced any order of germination in relation to any of the 

 communicable diseases. When a really living self-pro- 

 pagating thing goes through its phases of life and action, 

 like, for example, the yeast growth, we can trace it 

 through its course of action on organic substances, and 

 can study its effects, the changes it produces and the pro- 

 ducts of such changes. In the epidemic diseases we 

 have no such guidance, no trace of it. Their phenomena, 

 indeed, are opposed to the idea of the self-action of a 

 foreign vital material. 



Later Observalions on tlie Claitdiilar Theory. 



I turn again to a brief review of the glandular theory of 

 the origin of the contagious diseases, and of the advances 

 I have made in support of that theory during the period 

 of the past ten 5 ears. 



In that time I have seen no reason to change my views 

 on the subject of the glandular origin of the communi- 

 cable diseases. On the contrary, every new observation 

 has tended to confirm it and to make as I think the 

 demonstration of its truth the more definite. 



In continuance of observation 1 have noted that the 

 number of the distinctly communicable diseases is closely 

 related with the number of secretions. The poison of 

 hydrophobia is from the salivary secretion ; of diphtheria 

 from the mucous glands of the throat ; of scarlet fever 1 

 believe from the lymphatic glandular secretion ; of 

 glanders from the mucous secretion of the nasal surface ; 

 of typhoid from the mucous glands of the intestinal 

 surface; and so on. In some instances the blood itself 



is infected, and the corpuscular matter becomes the seat 

 of the catalytic change. 



A second point which has occurred to me is that the 

 matter or particle which sets up the poisonous action, 

 instead of being living matter, is matter actually dead, 

 and that its eftect for evil depends, in fact, upon its being 

 dead. I mean that the dead particles of organic matter in 

 contact with living are the cause of the physical change 

 which transforms the new particles of secretion into 

 poisonous particles as they are brought up to the infected 

 surface to be influenced by the infection. 



On the ground that the poisons are always of glandular 

 origin I have been led to the conclusion that under certain 

 influences affecting glandular action the poisons may be 

 made to originate directly through nervous impression 

 without the necessary intervention of an infecting particle. 

 In many epidemics it is common to see a number of 

 examples of the prevailing disease the origin of which is 

 traceable only to fear or anxiety. We call these nervous 

 cases, and we try to define them as such and as distinct 

 from cases due to contagion of a direct kind. But the 

 symptoms are the same as those which follow actual con- 

 tagion, and in epidemics of cholera they take even a fatal 

 character. My theory explains fully the reason of this. 

 It indicates that an extreme nervous impression acts on 

 the glandular nervous supply, paralyses the glandular 

 function, and thereupon produces the same phenomena 

 as is produced in other instances by the action of a specific 

 poison. 



The theory in this manner accounts for the origin of an 

 epidemic disease from an impression made on the nervous 

 system without the direct contact of poisonous matter, as 

 well as for the after-propagation of the disease by distri- 

 bution of poisonous particles when that is communicated 

 from an infected to a healthy person. It accounts equally 

 well for the production of disease and of a poisonous 

 glandular product under conditions of starvation and cold, 

 by which the nervous tension is reduced. Again, it 

 accounts for the production of disease and of a poisonous 

 glandular secretion under special atmospherical conditions 

 m which the activity of the atmospheric oxygen is reduced 

 in sustaining power. 



It has occurred to me further, as a result of the study 

 of the action of the poisonous particles, that when they 

 are brought into contact with the secreting surface, their 

 action towards the body at large is, in the first instance, 

 directly on the nervous fibre. The poisons act in the first 

 instance as irritants on the peripheral nervous surface, 

 and their effect may, I believe, extend particle by particle, 

 as by diffusion, through the whole length of the nervous 

 cord to the nervous centre. I have no doubt this is what 

 slowly takes place in hydrophobia. I believe this is what 

 takes place in diphtheria when paralysis is the sequel of the 

 acute symptoms of the malady. I believe the same mode 

 of progression of the poisonous influence is what happens 

 after inoculation with matter of small-pox, that the 

 severe nervous symptoms which mark the onset of that 

 disease are due to the extensive injury inflicted on the 

 nervous organisation, and that the diffusion of the erup- 

 tion over so wide a surface of the skin and mucous mem- 

 brane is the reflex on the peripheral nervous surface from 

 the nervous centres. 



It is worthy of special notice in connection with this 

 part of my subject, that in the communicable diseases 

 attended with an eruption on the skin or nervous surface, 

 the eruption, as a rule, takes a circular form. If it be a point 

 of vascular blush, a patechial spot, it is a rounded spot ; if 

 it be a pustule it is rounded ; if it be a more diHused rash 

 it commences in centres which are rounded points. This 

 appearance is an indication of nervous injury. The 

 rounded surface is the radius of injury done to the ner- 

 vous supply of that part. It is a paralysis of the centre 

 of nervous distribution over the affected part. My re- 

 searches on the influence of extreme cold on nervous 



