and efficiently in comparatively small doses, spread over many hours, night after night, until the quantity of particles of the "straw fungi" brought into contact with the respiratory tract with the in-breathed air will amount in the aggregate to as much as, if not more than, that which took effect when the paper of flax-seed meal was dashed in the face of his openmouthed patient. There was no difference in principle to deter him from connecting his case of accidental measles with an occurrence of ordinary measles. The only difference was in the mode of infection-the one affection being induced slowly through the cumulative effect of the fungi, whilst the other was set up instantly by overwhelming numbers of them-a mere matter of dosage, in fact.

Perhaps, however, the old leaven of contagion was too potent in Dr. Kennedy. He certainly steered dangerously near to heterodoxy in his views, but in those days, probably, it was not to be thought of that an artificially created disorder of the air-passages was actually of kin, related generically if not specifically, to a highly contagious disease occurring naturally in the regular order of things once in a man's lifetime. He got very close to this wild idea, but he stopped short. And, indeed, it would have been almost too audacious then to have entertained the proposition that a malady which for centuries, as everybody knows, has been handed down from generation to generation in one unbroken line from person to person solely by contagium vivum, is to be caused like some skin disease by low forms of vegetation. As it was, Dr. Kennedy went far enough, as he must have felt from the profound silence that was maintained in regard to his most instructive case. And he would seem to have taken the hint and to have sinned no more. He did not run any further risk by indiscreetly following up the subject. Therefore the phenomenon he brought under the notice of etiologists-a phenomenon that, rightly interpreted, not only afforded collateral evidence of the soundness of Dr. Salisbury's results, but gave strong support to his conception as to the implication of the "straw fungi" in the causation of ordinary measles (by bringing out what Dr. Salisbury had omitted to

K

show experimentally, namely, that the introduction of these fungi into the air-passages may induce morbilloid effects)—this striking phenomenon was allowed to drop quietly out of sight. It was an awkward fact that would not fit in with recognised doctrine; so it was got rid of.

This instance of the accidental creation of a morbilloid affection by the direct application of mildews or moulds to the airpassages, had not fallen in my way when I wrote the paper before referred to,1 or I should have seen yet more significance in the following extract from it:-"A curious case was related to me by a medical friend. A boy turned a lot of musty canary-seed out of a box, and, shortly after playing with it on the floor, was seized with violent irritation of all the mucous surfaces of the air-passages, with coughing, sneezing, &c. This was followed by a rash over the forehead and face, and the boy passed through all the stages of a disorder which could not be distinguished from ordinary measles.

"Measles was not present in the neighbourhood at the time. Other cases of a similar nature, supposed to have been caused by bran, pollard, chaff, &c., came under notice, but they were more obscure, or closely associated with measles epidemics."

With regard to these latter cases, I could not satisfy myself from the evidence to be obtained at the time whether the infected were, or were not, the subjects of measles taken in the ordinary way during the prevailing epidemic; but at this moment, having since learnt the particulars of other occurrences of a similar nature when measles were not prevalent, I have not the slightest doubt that all these disorders were morbilloid exanthems induced by the fungi growing on the bran, pollard, chaff, &c.

The infection of the two boys-the one with flax-seed the other with canary-seed fungi-are in a sense complementary ; for the measly eruption which was absent in Dr. Kennedy's case was present in the canary-seed case. This variationexamples of which are seen in most measles epidemics-was no doubt due to a difference in the fungal elements in the infective material. Although flax-seed is sometimes given to canaries, 1 Medical Times and Gazette, April 28, 1877.

the seed of the Phalaris grass is the food commonly given to them in this country. The difference in regard to the soils on which, and to the latitude and hemisphere in which the fungi were grown, accounts for a difference in the species of fungi in the material with which each boy was infected; and this difference again accounts for the differentiation in the symptoms of the two boys. It is out of the question to determine the species that were principally concerned in the parasitism in either of the boys, but the probabilities would seem to be that whilst the common moulds were represented both on the flax. seed and on the canary-seed, the spores of one or more of the Uredines or Ustilagines may have been present in the musty canary-seed. This is to be inferred as well from the appearance of the "rash," as from the nature of the vegetation from which the infecting fungi were derived. What the species of "straw fungi" taken in by the boys were, however, may pass; but it may here be observed that the occurrence of the eruptive fever in the boy in Australia brings us a step nearer to the mode of the occurrence of normal measles, and shows us that the period of incubation in this disease is governed chiefly by the dose of the poison.

The Rev. Edwin Sidney long ago referred1 in a lecture to the poisonous effects of fungi. An Ustilago, he mentions, that attacks grasses for hay, appears to be quite poisonous. Ustilago hypodites, he observes, a grass-smut, is most pernicious, and, according to Léveillé, the immense quantities of black dust given off in the hay-fields of France is disastrous at times, causing violent pains and swelling of the head and face, with great irritation. Of Penicillium Mr. Sidney says that it is the "mould on hay," and is found on bread, and also in the inside of casks, and that there is reason to believe its spores are poisonous; for two coopers who entered a great tun covered with this mould, to clean it, inhaled them and were seized with violent pains in the head, giddiness, and vomiting, which only yielded to severe treatment.

This case illustrates forcibly how a fungus, harmless under

1 Journal of Agriculture, 1849.

ordinary circumstances, may become extremely noxious by extraordinary concentration of its particles in the air—or in a large dose. Is it not a rational conclusion that prolonged exposure to an atmosphere holding the like particles in less numbers, but still largely in excess of the numbers usually floating in the air, would end by inducing similar though perhaps less intense effects?

In all of these instances of the injurious effects of fungi, as well in the case of the "reed fever" caused by handling Arundo donax, we have no knowledge of the species concerned in the several affections; but precision is not demanded. So far as the argument here is concerned, it matters not what fungus or fungi may have been implicated in any of these disorders. All that is important is that it should be established that the disorders resulted from the parasitism of some fungus or fungi. The identification of the species is essential to thorough elucidation of the subject, and will no doubt be undertaken sooner or later; but present nescience in this matter need not stop us from arriving at some extremely useful conclusions, if only we may safely take it to be a certainty that the infective processes now in question were set up by fungi.

Whatever doubts etiologists may have as to Dr. Salisbury's results and as to the Australian, cases, I apprehend that the accounts given by Dr. Kennedy as to the effects of the flax-seed meal, by Mr. Sidney as to the coopers, and by M. Baltus and M. Michel and by many other observers as to the disorders sometimes caused in man and the lower animals by contact with the larger reeds, are not to be disputed. If the main statements in connection with the modes in which these affections were brought about cannot be questioned; if they are accepted as facts, it is an inferential certainty that the inhalation of the spores of some species of fungi may be followed by noxious effects on the organism: and it is a corollary that these effects are caused by parasitism of the fungi.

CHAPTER XII.*

Exemption of children from measles during epidemics, due to their not getting a dose of the infection through the straw in their bedding being kept dry-Propositions as to exemption-Exemption of youths and adults from inefficient air-contamination.

SOME children have exemption from measles during epidemical periods, even when it rages in other rooms of the houses in which they live; and yet they lie, perhaps, upon straw. Again, the liability to contract measles diminishes after the age of ten or twelve years, though straw may still be used in the bedding. Grown up persons, too, who sleep on paillasses rarely take measles at epidemical seasons even if they have not had them. These facts and others relating to exemption (called very frequently immunity), though apparently inimical to, and inconsistent with, the view of straw fungi causation, are easily reducible to conformity with it: but some of them are extremely inconvenient and even embarrassing to the pure contagionist, who, as we shall see, is put to great shifts to accommodate them to his theory; and, indeed, can only do so by falling back on special interpositions, or on actual suspensions of natural laws on behalf either of a particular class, or of a particular individual here and there in all classes. "Insusceptibility" is the cloak loosely thrown over all these awkward, irregular, exceptional cases. It is made to cover them after a fashion and has answered its purpose indifferently well; for etiologists and epidemiologists have not cared to pry too curiously under it into this gift of immunity.

By the "straw mildew theory" all cases of so-called immunity