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produced in such a manner that it can excite an immediate defensive reaction in the glands it is passing through, the chances that a septicemia inay result as the consequence of the normal flow of lymph are not entirely disallowable.

There is however the question of chemotaxis to consider. Not only will bacilli cause a migration of leucocytes towards an infected spot by virtue of t he toxins they produce but the bodies of bacilli are capable of causing this by them- selves.

If the plague bacillus does not start an immediate defensive reaction in a gland to which it may be carried, by virtue of a toxin, it may therefore still bring this about.

The plague bacillus is a parasite, at any rate during times of epidemic plague and it does not seem unreasonable to suggest that it may acquire a power to lessen it chemotactic action on the leucocytes in order to facilitate its passage through the glands.

Support for this view may, I think, be found in the observations that before an outbreak of plague is recognised in a locality there sometimes occur cases of lymphadenitis which end in recovery and which are not recognised as plague.

Might not the bacillus at such a time be prevented from entering the general circulation by reason of its chemotactic effect and further might it not gradually acquire a habit of diminishing this effect in primarily infected glands or chains of glands and so become more virulent?

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There are still other points to be considered. NUTTALL in his work on Blood Immunity and Relationship says: "According to Erlich (1901) toxins enter into specific chemical combinations with the protoplasm of certain cell groups* *****” and again under the heading Antibodies in General" he says: "It appears that all antibodies are formed on the same general principles, although they may possess different properties. Wherever they are formed the substance must be assimilable which gives rise to their formation."

If this theory be accepted it is difficult to imagine that an extra-cellular toxin is not produced by the bacillus, at any rate in the blood, for an intracellular toxin until set free could hardly be held to be sent in an assimilable form.

The high degree of immunity induced in the horse under the treatment for the production of Yersin's Seram points to the presence in the blood of that animal of an assimilable toxin, and if this were only set free on the disintegration of the bacilli we should seemingly have the parodox of an aminal being most strongly poisoned at the very time that its hood was producing its strongest bacteriolytic effect.

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According to R. Muir “***** No important bacterial toxin is as yet "been obtained in a pure condition, and though many of them are probably

of pro- "teid nature, even this cannot be asserted with absolute certainty" and further, Attempts to get a pure toxin by repeated precipitation and solution have resulted "it the production of a whitish amorphous powder with highly toxic properties, "Such a powder gives a proteid reaction, and is no doubt largely composed of "albumoses, hence the name toxalbumose has been applied. The question has, how- "ever, been raised whether the toxin is really itself a proteid, or whether it is not "merely carried down with the precipitate. With regard to the nature of intracel- "lular toxins, there is even greater difficulty in the investigation and still less is

known.

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While therefore the production by the plague baillus in corpore of an assimi- lable toxin is not proved to be impossible, it is clear that very little is known with certainty on this subject. At any rate there is not any evidence to directly nega- tive the suggestion I have put forward above as to the possibility of the plague bacilli gaining entrance to the blood stream through the normal lymph flow for seeing that the plague bacillus is not classed as a pyogenic organism and that so little is really known as to the nature of its toxin there is not sufficient ground for holding the opinion that any bacilli which may be brought to a lym- phatic gland by its afferent vessels must be necessarily and entirely arrested in the glandular tissue.