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As regards the view that lethargic encephalitis is merely a manifestation of influenza it appears
(Medical Science, May, 1920, p. 115), that opinion in Italy, Germany and America has recently been
expressed directly in support of it, but that in Vienna the contrary attitude is still maintained. A recent
paper by Dr. Bramwell (Lancet, 29. v.20), giving his experience in Edinburgh, is instructive in this
connection ; his facts appear not dissimilar from those supplied by the first three countries, but his final
conclusion tallies with that from the town last named.
There has been further discussion as to the nature of the link which binds together members
of the influenzal group of diseases. Newsholme has urged, in objection to my " seductive hypothesis,"
as he terms it, that the diseases in the group are associated because each one of them (and he would
include measles and whooping-cough also) is favoured by identical climatic conditions (Proc. Roy. Soc.
Med.,Vol. XII., p. 6). Such a contention assumes that they all prevail together (this of course is certainly
not the case if measles and whooping-cough are included in the group), and overlooks the fact that in a
broad view the true associated epidemics occur for the most part before and after, and only in limited
degree contemporaneously with, pandemic inflenza.
With regard to the associated prevalences of disease which are encountered coincidentally with
influenza in its pandemic phase, the main argument in favour of there being a common infecting agency
for all of them is, of course, that which I ventured to apply in the Discussion on Influenza of November,
1918 (loc. cit., p. 26). The notion that everything must be explained as being the outcome solely
of continuous variation in the germ, can clearly be ruled out of court. There remain two fairly obvious
possible lines of investigation ; the first the " skiey influences " hypothesis, which, however, is hedged
about with very serious difficulties; the second the hypothesis tentatively examined in the Appendix
to last year's Annual Report and in communications to the Royal Society of Medicine (Vol. XII., Sect,
of Epidem., pp. 72-73, and Vol. XIII., Sect, of Epidem., pp. 182-183). It is assumed, therein, that influenza
represents the sum total of the phenomena produced by the " interplay between, on the one hand,
and ultra-visible virus mutating within the cycles of its multi-annual and seasonal periodicities, and on
the other hand the varying reactions exhibited by communities more or less immunized or sensitized."
Recent bacteriological literature testifies to the fact that, thanks to Twort, Penfold and other
workers, mutation, which was regarded ten years ago as rank heresy, is now looked upon as tne of the
most important of the phenomena demanding investigation, in connection especially with the determination
of specific characters.
The investigation of the potentialities of the ultra-visible viruses is a much mo e formidable task,
but it seems as though it can only be by study of these most elusive forms of life that further advance
becomes possible. Mr. F. W. Twort in a paper published in the Lancet of December, 4, 1915, has made
a beginning; he has cultivated glycerinated calf lymph on agar and has produced " watery looking
areas," which seem to represent either a " condition or disease of a micrococcus," and to be due to some
stage in the life cycle of the micrococcus, or to an enzyme secreted by the micrococci and leading to their
destruction. He speculates, further, as to the nature of this ultra-microscopic virus ; it may, he says,
" belong somewhere in the vast field of life more lowly organised than the bacterium or amceba. It may
be living protoplasm that forms no definite individuals, or an enzyme with power of growth." I confess
this last conception has a special fascination for me, for it once fell to my lot to obtain material " capable
of manifesting ferment powers altogether apart from the coincident growth and development in it of
visible micro-organisms " (Supplt. to 21st Ann. Rep. of L.G.B., 1891-1892, pp. 204-205 and 208).
Similar results to those of Mr. Twort have been recently reported by F. D'Herelle, who grows
an invisible organism (or bacteriophage as he terms it), which attacks Shiga's dysentery bacillus.
T. Kabeshima has tested D'Herelle's conclusions, and inclines to the view that the bacteriophage is
not a living virus but a " ferment " (see Medical Science, Vol. II., No. 2, pp. 182-183).
It may be hoped that more will be heard of the work of Twort and D'Herelle, and that thus
further light may be thrown on the hypothetical mutating ultra-visible virus of the influenzal group
of diseases.
There remain now to be considered two further papers dealing with certain other aspects of the
influenza problem. (1) Some American experiments on the transmission of influenza, which clearly
demonstrate by laboratory methods the immunising influence of exposure to influenza, even when not
followed by an actual attack of the disease. (2) The report on cerebro-spinal fever by Col. Dorgan,
which was ultimately published towards the middle of 1919. It will then be necessary in conclusion
to say something concerning the manifestations of the influenzal group of diseases subsequent to the
decline of the epidemic of February-March, 1919, described in last year's report.
The experiments, recorded by Dr. Milton J. Rosenau, were performed, on Gallops Island in Boston
5 Harbour, on volunteers obtained from the Navy (Journal of the American Medical Association, Aug. 2,
1919). " None of these volunteers, 100 all told, had ' influenza,' that is from the most careful histories
that we could elicit, they gave no account of a febrile attack of any kind during the winter."
Experiment I.—To each of 19 volunteers, a large quantity of a mixture of 13 different strains
of Pfeiffer's bacillus, some of them obtained recently from the lungs at necropsy, was administered
—suspensions of the organisms being sprayed with an atomiser :nto the nose, and into the eyes, and back
again into the throat, while the volunteers were breathing in—some billions of the organisms were used
on each one of the volunteers — but " none of them took sick."
Experiment II.—Virus obtained from cases of the disease, material and mucous secretions
of the mouth and nose and throat and bronchi being transferred to the volunteers. Ten volunteers
each received one c.c. into nostril, throat, or on the eye. " None of these took sick."
Experiment III.—A larger amount of material was obtained and was rushed down to Gallops
Study of
ultra-visible
viruses.
Experiments
to determine
mode of
spread of
influenza