With these discoveries, the mystery of the new blight vanished. An examination of the soil of stricken areas showed that it swarmed with colonies of B. diazotans—to use the customary medical contraction—and the whole secret of the destruction was revealed.
It was evident that these new and super-active bacteria attacked the soil, disintegrated all the nitrogenous compounds within their range and thus left the plants without nourishment. The death of the plant followed as a natural result; but the matter did not end there. By destroying the nitrogenous compounds in the soil, the bacteria altered the whole texture of the earth in which they grew. All the nitrogenous organic matter which forms so large a part of the binding material of some soils was destroyed utterly; with the consequence that the mineral particles, which previously had been resting in an organic matrix, were now free to move. Only the clays retained their tenacious character: all other soils degenerated into sand.
There has, of course, been a great deal of speculation upon the origin of B. diazotans. Hartwell suggested that it came to us from Venus, propelled by light-pressure across the abysses of space. Inshelwood put forward the view that in B. diazotans we had an example of bacteria, originally endemic, changing their habits and spreading into fresh regions.
Personally, I believe neither hypothesis. I feel sure that I saw the birth of the first B. diazotans on that night in Wotherspoon’s laboratory, under the action of the fireball; and the evidence is simple enough.
Every living creature is a wonderfully constructed electrical machine. Each beat of our hearts, each systole of our lungs, each contraction of a muscle in our frame produces a tiny electrical current. Our organism is a mass of colloids and electrolytes which transmit these charges hither and thither throughout our systems; and were we gifted with an electrical sense in addition to those which we already have, we should see each other as complexities of conductors along which currents were playing with every movement of our body.
This complex electrical system is acutely sensible to external electrical conditions. Anyone who has held the handles of an induction coil or who has taken a spark from a Leyden jar knows the physiological effects which these things produce. The influence of high-tension currents upon the growth of plants has been proved beyond dispute.
Now it seems to me that in this effect of an external electric charge upon the internal mechanism of an organism we have a clue to the origin of these new bacteria. I have already told how the fireball, in its explosion, shattered the denitrifying cultures in Wotherspoon’s room; and it seems clear that at the moment of the concussion there must have been a tremendous play of electrical forces about the spot. We know hardly anything with regard to the nature of the electrical fields existing in such things as these fireballs; and it is quite possible that they may be different from anything of which we have any knowledge among the more usual displays of electrical energy. I believe, then, that it is in the action of the fireball that we must seek for an explanation of the change in habit of Wotherspoon’s denitrifying bacteria.
Again, I have mentioned my observation of the rapid multiplication of the denitrifying bacteria which I made with Wotherspoon’s microscope on the following day. That also seems to me to have a bearing upon the problem; though I admit quite frankly that my evidence is only that of a layman. It is in every way regrettable that Wotherspoon, having tired of using his room as an exhibit, should have cleared away every trace of the wreckage before any expert examination of it could be made; for in this way the crucial evidence on the point was destroyed.
Further, in support of my views, I would point out that the very first known occurrence of B. diazotans was that which had Regent’s Park as its site; and that the first place of attack was in the immediate neighbourhood of Wotherspoon’s house in Cumberland Terrace. This can hardly be disregarded, when it is considered in connection with the other facts which I have mentioned.
At this time of day there can be no question that London formed the focus from which B. diazotans spread throughout the world. I have described the ramifications of the great air-services; and it seems to me obvious that the organisms were carried to and fro upon the surface of the globe by the agency of the aeroplanes. The order of attack at various points indicates this very clearly, in my opinion. First came the American and Egyptian outbreaks; then Uganda and South America; and finally, long after the others, Australia showed traces of the devastation. I have checked the possible dates of arrival in these various places, taking into account the relative swiftnesses of the aeroplanes on the different routes; and the results can hardly be gainsaid. Allowing, as one must, a certain latitude for the time of development of the microbe in various spots, there seems little doubt that the dates of the outbreaks fell into the same succession as the times of arrival of the various London air-services.
IV
Panic
In dealing with the subsequent stage of affairs in this country, I feel myself at a loss. Matters of fact, sequences of events, definite incidents in a chain of affairs: all these can be described without much difficulty and with a certain detachment on the part of the narrator. But when it comes to indicating the transition from one psychological
