have been infected to a slight extent by the sum of the spores they directly imbibed, it is an inference that complete or efficient infection occurred indirectly, by the spores detached from the mouldy bread, and by those which passed through the animals, finding abundance of congenial soil and highly favouring conditions for rapid growth and extension in the sty and for causing efficient air-contamination. But the whole matter is at present in the dark.

Professor Klein has avoided the course taken by C. Harms and has not essayed to show where the bacilli of swine fever come from. It is to be presumed they occur somewhere in nature; unless, as before suggested, they are to be supposed to be now found only in the contagium. But as this view is not worked out by Professor Klein, we are left uncertain as to the sources of these bacilli. The species, however, has been added to its genus. That work is done.

It is doubtful whether swine plague or swine erysipelas is the analogue of measles, though it would seem on the whole more probable that the latter is; but from Professor Klein's descriptions of the variations in the lesions of the animals he examined, and from the accounts of other observers on like points in regard to both affections, it is obvious there must be a good deal of overlapping, not only as to these two, but as to each of these and other porcine diseases. And this admixture of infections is exactly what might be expected from the surroundings of domesticated swine. The diversity in the forms taken by pathologists to be the pathophytes of swine plague has its interpretation in the differences in the parasitic vegetation entering swine at different times and places; and among the forms of vegetation specially indicated as being more frequently implicated perhaps than others in the diseases of these animals are what have here been called the "straw fungi." In most countries swine are kept in straw of some kind which may be in any state of filth; and they will thus be of necessity. largely exposed at certain times to whatever noxious influences an atmosphere contaminated with "straw fungi" may have upon them. I conceive therefore that the inoculation of pigs

with these fungi and the submission of them to air heavily charged artificially with their spores, would serve to clear up many obscure points connected with the causation of the diseases of swine, and to suggest practical modes for their prevention-to say nothing of the "shaft of light" they would throw on the cause of measles and other diseases.

Wherever cattle are housed and straw is supplied to them for bedding, it is an inference that they will be liable to contract whatever diseases represent measles and their congeners. It was long ago seen by one observer that under certain peculiar conditions measles and cattle disease occurred together; and he suspected they were due to a common cause. Dr. Copland in the article on measles in his Dictionary says:-"The probability of its origin in a miasm proceeding from numbers of persons breathing a confined air with their cattle, has been hinted at by Hildenbrand: 'In diversis ac dissitis villis, præsertim in vaccarum stabulis, in quibus plures sæpe familiæ unacum prolibus unitæ totam ferme transigunt brumam, morbillosum emicare vidimus contagium eousque vigens, donec plurimis individuis infectis, talique pacto hominum dispositione extincta, exhausto igitur quasi solo, in quo radices figere posset, in lethargi speciem cadat, data recenti occasione denuo ad activam vitam surrecturum. Nostra quoque sub zona huncce fomitem contagiosum in morbis catarrhalibus gravioribus, opitulante constitutione annua, vel specifica plurium hominum et animalium cohabitantium mephite, primitus oriri posse, conjectura quidem foret, nobis omnino non improbabilis, quam tamen ob defectum observationem defendere nondum auderemus.'"

In point of fact, although Hildenbrand is careful to tell us he was not then in a position, through lack of observation, to defend so unorthodox a proposition as that a specific poison might arise from the cohabitation of a number of men and animals and cause measles (de novo); yet it is obvious that he leaned over to that conclusion. But not to discuss this side issue, Hildenbrand at all events shows clearly that the " graver catarrhal diseases" attack both man and beast when housed together

in the winter, and leaves it to be inferred that the diseases in both are caused by the same morbific agent. And although men rarely herd with cattle in English-speaking communities, yet they are both subject to the "graver catarrhal diseases" at the same time in certain seasons; no doubt from a like or similar specific poison. For which reason I submit that the inoculation of cattle with the "straw mildews," or the artificial introduction of the vegetation into their air-passages, would result in the discovery of the analogue of measles in the animals.

But enough has been advanced to show how the experiments of Dr. Salisbury might have been brought to bear on the botanical side of the question of the relation of pathogenic to other forms; and without having recourse to the human subject. If Dr. Salisbury cannot be said to have shown, and he did not claim to have shown, that measles are caused by the "straw mildews," I hold that he proved by his inoculations that, under certain conditions, they will cause an exanthem similar to measles. It is an inference therefrom that the fungi inoculated by him underwent morphosis into forms similar to the pathogenic forms that have been found by observers in measles patients; and that the forms present in the artificially caused exanthem were in organic continuity with the inoculated straw fungi. The soundness of these inferences might have been tested equally as well on the domesticated animals as on man. Not only might the simple and comparatively narrow issue as to the pathogenic effect of the "straw fungi" have been tried on them, but the wider or more important issue as to the conversion of these fungi into bacteria or bacteroid forms: and this latter is the wider and more important issue just now because of its bearings on the question of the status of all pathophytic forms.

CHAPTER IX.

The kind of vegetation in measles infection-The Uredines and Ustilagines and the common moulds-The "straw fungi" proper cause the rash and desquamation, probably, and the common moulds add to the catarrh and fever-By variation in soil, and by the presence or absence of species, all types of measles to be accounted for-The theory gives an intelligible view of causation, and a good working plan of prevention-The doctrine of contagion does neither-The congeners of measles derive from "straw fungi"-Other diseases caused by fungi grown in the bed.

BEFORE examining the phenomena connected with the occurrence of measles, it is necessary to give some of the inferences here reached as to the infective vegetation and as to the modes by which it becomes an efficient cause of the disease.

First as to the kind of vegetation. The conclusions arrived at on this matter will have been sufficiently indicated, perhaps, but it may be stated definitely that it is inferred that most, if not all, of the fungi specially addicted to wild and cultivated grasses and their allies, will, or may, cause symptoms in man of a more or less measly character; but that although the spores given off from the fungi during their existence on living or growing plants may, as we see in farming operations, cause morbillous or morbilloid complaints, yet the spores which come from fungi occurring on the dead portions of cereals, grasses, &c., are almost exclusively concerned in causing measles.

It would be superfluous to give the numerous species that naturally attack, or that have at some time or other been found on grasses. It is enough to say that although any one, or more than one, of these fungi may, possibly, under exceptional cir

cumstances, have a share in the manifestations seen in a given case, or in a number of given cases, yet under the ordinary conditions of life, in towns especially, the probabilities are that the number of species concerned in the great majority of cases of measles is limited to four or five, or less. It will be understood that the latitude, the altitude, and the seasonal and other general conditions of a locality will generally determine, not only what species of these fungi shall be concerned in an isolated occurrence, or in a general outbreak of measles, but in what proportion each species shall be represented in the sum of the infective material causing the disease. The species most commonly involved in morbillous affections are perhaps included in the Uredines and Ustilagines. In addition to these fungi, however, it is to be inferred that the straw of wheat, barley, oats, and rye, and such dried grasses, flax, maize, rushes, sedges, &c., as may be used as bedding, will, or may, sooner or later be overrun with the common moulds; and that the spores from these go to swell the amount of contamination of the air.

It is an inference that some one or more of the "straw fungi " proper are concerned chiefly, if not wholly, in the rash and desquamation of all morbilloid exanthemata and their congeners, and that the common moulds share with them in the general catarrhal effects. At the same time it is difficult to appreciate the changes that may be undergone by some of the latter forms on matrices sodden with different kinds of filth; and, having in view some debateable points in dermatology, it would not be safe to say that they are to be regarded as being incapable of inducing specific effects on the skin. Yet on a review of the whole question with present lights, the probabilities would seem to be largely in favour of apportioning the morbillous effects to their specific causes as above; namely, the rash to the mildews, the catarrh and the fever to both the moulds and the mildews.

The disposition of organic material in and about habitations (including the excreta-disposal systems of peoples) has a relation to the incidence of measles; but setting aside for the present this factor in the spread of the disease, I submit that the sup

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