TRANS AC'flONS OF THE SECTIONS.. 153 



Oil the Graft Theory of Disease. 

 % James Eoss, M.D., Waterfoot, near Newehurch. 



The active part of viraleut fluids has been proved by the experiments of Prof. 

 Chauveau and those of Dr. ]3iirdon Sanderson to reside in particles not larg-er than 

 tl»<5 .ToJoo of 'i;! iiith in diameter. These particles are admitted to be living-; and 

 the question arises whether they form a race of independent beings like Bacteria, 

 or are merely modifications of the organism from which they have b'ecome detached. 

 The former view constitutes the basis of what is called the germ-theory of disease, 

 while the latter view is adopted here; and this constitutes at once the grounds and 

 the justification of the title— the Graft Theory of Disease, In the absence of 

 direct experimental evidence to decide between these different opinions, our only 

 alternative is to develop as much as possible the indirect evidence. On the sup- 

 position that the contagion particles are merely modified portions detached from 

 a living organism, there is a close similarity between them and the reproductive 



Eai-ticles. Both sets of particles are merely modified epithelial cells ; they also 

 ecome detached because the supply of nourishment fails them, and both are 

 characterized by being imspecialized. In the reproductive particles there is a 

 union between two particles detached or semidetached; but in the case of the 

 genesis of a contagious disease there is a union between a distinct individual and a 

 detached portion of another individual. In this respect, therefore, the analogy 

 fails. But the phenomena of vegetable grafting agree even in this respect with 

 those of the contagious diseases. Dr. Masters says that " cases have been observed 

 wliere from the stock below the graft fruits and flowers of the same appearance as 

 those borne on the scion have made their appearance." Again, Mr. Darwin savs 

 that " when the variegated jessamine is budded on tlie common kind the stock 

 sometimes produces buds bearing variegated leaves." This shows that the scion 

 attects the stock not only at the point of contact, but that it communicates to it a 

 chan.ge which manifests itself throughout the entire organism of the latter ; and 

 this is one of the most remarkable features of contagious diseases. 



But if virulent fluids are merely modifications of healthy tissues, the effects 

 produced by them upon another organism should correspond in certain leading 

 particLdars to those of other morbid tissues. If we compare the primary pustule in 

 inoculated smallpox yni\\ the pustule caused by tartar-emetic ointment, we shall 

 find that they go through a more or less smiilar evolution. An areola, or inflam- 

 matory ring, surrounds them, which is large and well-marked in the former, but 

 is also present in a minor degree in the latter. The former can be communicated 

 by inoculation to a healthy individual, but ordinary inflammation has also been 

 communicated in a similar manner. The lymphatic' glands in the Aicinity of the 

 smallpox-pustule become swelled, but this is only what occurs in the case of 

 almost all local diseases ; and the character of the glandular affection always cor- 

 responds with the local disease which has excited it. This is well seen in syphilis, 

 tubercle, and cancer. The lymphatic enlargement in smallpox, therefore, p"resents 

 no peculiarity which does not occur in other diseases ; but in other diseases, such as 

 pviemia, tubercle, and cancer, secondary aflectious occur in the lungs, liver and 

 internal organs generally. The secondary aftectiou in inoculated smallpox, how- 

 ever, takes place on the surface of the body. This is probably owing to the special 

 alfiuities of the tissues for special substances. It is also necessarv in all highly 

 contagious diseases that living particles should be detached in large numbers from 

 the body; hence secondary affections must occur in such diseases on either the 

 external or internal surface of the body, otherwise the disease would die out. The 

 fever is not, of course, peculiar to smallpox : it is alwavs an accompaniment of 

 rapid tissue changes; and the fever is higher in smallpox and the contagious 

 diseases generally, just because there is more rapid cell-nmltiplication througTiout 

 the body. Such changes mean an augmentation of the molecular forces devoted to 

 growth at the expense of those devoted to structure and function, and what is not 

 expended in the latter goes to the genesis of heat. But rapid cell-multiplication 

 involves other morphological changes : these are diminished bulk of units, disap- 

 pearance of cell-wall, and discontinuous growth; and such are proved to be the 

 characteristics of virulent fluids. Smallpo.x has, therefore, a close affinity with 



