6 ARTIFICIAL PRODUCTION OF TUBERCLE. 



The mode of inoculation was one which I learned from my friend Dr. 

 Sanderson : to take a very small trocar fitted with a piston longer than the 

 trocar; push up the sharp end of the trocar a small piece of the material 

 (and I have never introduced a piece larger than a canary-seed or hemp- 

 seed) ; introduce the trocar under the skin, and push the piston down till 

 the material is delivered under the skin, and retained there. When fluid is 

 used, I have used a small injecting-syringe with rather a large nozzle. I have 

 never, under the latter circumstances, used more than two or three drops. 

 The site of inoculation has almost invariably been the nape of the neck. 



I may add that I placed the animals under healthy hygienic conditions 

 in a large wooden shed, looking to the south, thickly protected with felt 

 from the frost, provided with a window, and with access to a paved and 

 sloping yard, exposed during the whole day to the sun. The house was 

 divided into two parts — one containing the animals that had been inoculated, 

 and one for the others. They were abundantly supplied with food, and their 

 conditions have been, I think, as healthy as possible. 



I will now proceed to describe in detail the anatomical effects which 

 have followed the introduction of the materials in this manner. I must, 

 however, state at the outset, that the appearances now to be mentioned as 

 having been observed either locally or in internal organs, apply to all cases 

 in which I have succeeded in producing what I consider tubercle, whatever 

 be the material employed; for except in those cases where the inoculations 

 were ineffectual in producing changes in internal organs, no differences could 

 be observed either by the naked eye, or by microscopic observation, in the 

 effects which followed. 



To commence with the local effects, there are two which are rare. One 

 of these is, that a slough is produced in the neighbourhood, which sometimes 

 proves speedily fatal, with no further disease of organs than an inflam- 

 matory enlargement of the neighbouring lymphatics, totally different in 

 its character from what I consider as a tuberculous change. The lymphatics 

 are then swollen, soft, and more opaque than natural, but not cheesy, 

 indurated, or suppurating. The other, which also is rare, is local suppuration. 

 Now, in the guinea-pig, local suppuration — that is, the formation of diffused 

 or circumscribed abscesses — is, comparatively with the rabbit, extremely rare. 

 In the rabbit, it appears to be more common. The most common result is 

 the formation of masses of cheesy matter, which are dry and friable, some- 

 times offensive when ulceration has taken place externally through the skin, 

 but hardly ever presenting a soft puriform fluid. Under the microscope, the 

 material so formed has all the usual characters of cheesy matter, showing 



