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since by Drs. Brett and Bird, and may be considered the result of the exudation of serum from the over-distended blood-vessels. In the advanced stages of inflammation, the sputa become opaque, either from pus cells multiplying, or from the albumen coagulating into a curdy matter. In some cases the albumen coagulates as secreted, forming opaque films or flakes; and where these occur to a large amount, they unite to form the pellicular or croupous matter, which may take the forms of the bronchial tubes, ramiform, or arborescent. When thus tough and consistent, they probably contain also fibrin and sarcophytes, being like the false membranes thrown out on serous surfaces; but in the looser and more curdy varieties, these exudations have a nearer resemblance to the albumen or casein coagulated from eggs or milk. In the expectoration of certain phthisical patients, this curdy or shreddy matter predominates so much as to constitute a variety; and it probably proceeds from a croupous or albuminous exudation from the parts of the bronchial membrane contiguous to cavities, rather than from the cavities themselves.

The hæmorrhagic variety of phthisis is that in which, more or less constantly, blood appears in the expectoration. As this subject will be noticed in a special chapter, we need not dwell on it here further than to point out its connection with the first stage of pneumonia, in which the sputa are tinged with hæmoglobin, often altered; and the common persistence of red corpuscles in their entire state in certain other varieties of phthisical sputa in connection with scurvy and purpura. In all these different cases, the hæmoglobin, like the other matters, may be superseded by the pus formation or caseation. The abundance of this hæmatin is the cause of the dark brown or green colour of phthisical sputa sometimes brought up before death. The colouring matter exuded by the moribund congestion is even then undergoing conversion.

CHAPTER XIII.

VARIETIES OF CONSUMPTION-continued.

Phthinoplasms in the lymphatic system—Production of Tubercle by inoculation-Observation of Laennec-Experiments of Villemin, Andrew Clark, Sanderson, and Fox-Analysis of results-Causes of success and failure considered-The most infecting matters either phthinoplastic or septicLocal effects of inoculation-Lymphatic or adenoid system first infected— then organs-Observations of Drs. Sanderson and W. Fox-Infection aided by septic influences in the body or in the air.

WE have now gone through the consumptive elements which originate from the sanguiferous system - the phthinoplasms from inflamed or congested blood-vessels. We have next to notice those which have their origin and chief seat in the lymphatic system-that remarkable supplementary apparatus which is at once the feeder and the scavenger of the flesh and blood of the body. We have already, at some length, endeavoured to trace the origin of disease in the lymphatic glands and other portions of the so-called adenoid tissue to a change in their most vital and characteristic element-the germinal matter, or sarcophytes. And to enable us to understand how this change may be brought about independently of inflammation, we now have to bring to our aid the subject of infection, and the modern discoveries on the artificial production of tubercle.

The idea of the possibility of producing tubercle by inoculation originated with Laennec. I have several times heard him relate what happened to himself twenty years before: how that, in opening some vertebræ affected

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with tubercle, the fore-finger of his left hand was slightly scratched by the saw. The next day a little redness appeared, and there formed gradually after, a little swelling under the skin, of the size of a large cherry-stone. In eight days the skin opened at the scratch, and there appeared a yellowish compact body, exactly like crude yellow tubercle. After cauterising it with butter of antimony, which gave hardly any pain, he gently squeezed out the contents, which, being softened by the liquid caustic, exactly resembled softened tubercle. After repeating the cauterisation to the remaining little cyst, the wound healed, without further inconvenience. I may remark that Laennec died of phthisis; and during the year before his death, when I attended his clinique, although full of vivacity and intelligence, he had the wasted aspect of one in advanced disease.

The subject seems to have received no further attention till about seven years ago, when M. Villemin, led by various considerations to suspect the infectious nature of tubercle, performed experiments on animals to determine whether it could be produced by inoculation. The matter of tubercle, grey and yellow, was inserted under the skin of rabbits and guinea-pigs; and in the course of from two to six months the animals were killed, when tubercles, both grey and yellow, were found in the lungs, liver, spleen, lymphatic glands, peritoneum, and other parts, the yellow being most manifest in the animals that lived longest. These experiments have been repeated and varied by many competent observers in France, England, and Germany, and with a concordance of results so general, that no doubt can be entertained of the fact that grey tubercles, in all respects resembling those spontaneously occurring in the human subject, affecting the same structures, and liable to the same changes, may be artificially produced in certain animals by the insertion of tubercu

lous matter in any form under the skin. This result seemed at first to countenance M. Villemin's idea that tubercle depended on a specific poison, the infection of which was communicated from one animal to another. But as experiments were multiplied and varied, it was found that the subcutaneous introduction of not tubercle only, but of other matters, as pus, putrid muscle, and diseased liver, from non-tuberculous subjects, was equally followed by the production of tubercles in several organs. This was first announced by Dr. Andrew Clark,' and confirmed, subsequently, by Drs. Burdon Sanderson 2 and Wilson Fox. Further, it was proved by both the last experimenters that, without any inoculating matter at all, the introduction of a mesh of clean cotton thread, as a seton, into the skin of a guinea-pig, was followed by the production of tubercles in the lungs and other organs. Dr. Fox has given a tabular view of the results of his experiments, and from this we will give extracts, from which some estimate may be formed of what agents prove most efficient in producing artificial tubercle.

Of 8 inoculations with tubercle, 6 succeeded, 2 failed. Of 11 inoculations with various pneumonic products. (red pneumonia in tuberculous patient, grey infiltration, 'scrofulous,' yellow, cheesy, and chronic), all succeeded.

Two inoculations with sthenic pneumonia failed.

Four inoculations with sputa of chronic bronchitis and acute pneumonia failed.

Of 2 inoculations with phthisical sputa, 1 succeeded, 1 failed.

Of 17 inoculations with pus from various sources, 7 succeeded: comprising, 1 each from injury to knee, sup

1 Med. Times and Gazette, 1867.

2 Tenth Report of the Medical Officers of the Privy Council, p. 150 (1868). The Artificial Production of Tubercle in the Lower Animals (1868).

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purating bone, and lumbar abscess; 3 out of 5, of foul pus; 1 out of 2, from scrofulous bone.

Of 11 inoculations from acute inflammations, 4 were successful, 2 being from pyæmic abscess of spleen; 1 out of 2 from unaffected part of same spleen; and 1 out of 2 from sloughy wound.

Of 9 inoculations from matters from chronic inflammations, &c.,' 6 succeeded: 2 of gelatinous inflammation of knee; 3 of lardaceous liver; and 1 of cirrhosis of kidney.

Of 12 cases of reinoculation from tuberculated animals, all were successful.

Four cases inoculated with vaccine matter succeeded. Of 5, with putrid muscle, 4 succeeded.

Of 4, tried with seton, 1 succeeded.

Of 3, with cotton thread, 1 was successful.

Of 10 trials with matter from syphilis, typhoid intestine, and cancer, all failed.

In these trials, we find that the materials most efficient in producing artificial tubercle were those from low pneumonia, pyæmic abscess, gelatinous inflammation of knee, lardaceous liver, reinoculation from artificially tuberculated animals, and vaccine matter. Less constantly successful were human tubercle, phthisical sputa, foul pus, putrid muscle, and cotton thread and seton; whilst no results were obtained from material from acute sthenic pneumonia, pneumonic and bronchitic sputa, healthy abscess, diphtheria, various inflammations in rabbit, syphilis, typhoid intestine, and cancer.

Whatever be the influence which determines the production of tubercle, that it is nothing specific in the materials which succeed in producing it is obvious from their varied nature-tuberculous and non-tuberculous, animal products and mechanical injuries. But it is impossible to avoid seeing the close analogy which this pro