To take yet another instance, and one which has a more intimate bearing upon the experiments to be discussed. Some years ago Dr. Charlton Bastian claimed to have proved experimentally the fact of abiogenesis, or the generation of living organisms from non-living matter. He had placed various organic infusions in glass tubes, which were heated to the boiling point and then hermetically sealed. When the tubes were, after a certain interval, unsealed, the contained liquid was found in some cases to be swarming with bacteria. Believing that these micro-organisms and their germs were invariably destroyed by the heat of boiling water, Dr. Bastian saw no other conclusion than that the bacteria were formed directly from the infusion. His conclusions were not accepted by the scientific world. But they were rejected, not because the fact of abiogenesis was regarded as in itself improbable, nor yet because Dr. Bastian was unable to indicate by what steps or processes the transformation of an infusion of hay into living organisms of definite and relatively complex structure could be conceived to take place, but because Pasteur, Tyndall, and others showed that the germs of some of these micro-organisms are capable of sustaining for some minutes the heat of boiling water; and further, that when elaborate precautions were taken, by filtering and otherwise purifying the air, tubes containing similar infusions would remain sterile for an indefinite period. The conclusion that under certain conditions thought-transference may occur rests upon reasoning similar to that by which Dr. Bastian sought to establish a theory of abiogenesis. Neither the organs by which nor the medium through which the communication is made can be indicated; nor can we even, with a few trifling exceptions, point to the conditions which favour such communication. But ignorance on these points, though a defect, is not a defect which in the present state of experimental psychology can be held seriously to weaken the evidence, much less to invalidate the conclusion. That conclusion rests on the elimination of all other possible causes for the effect produced. But at this point the analogy between the two researches fails. Dr. Bastian's conjecture was based on a short series of experiments conducted by a single experimenter under one uniform set of conditions. At the first breath of criticism the whole fabric collapsed. The experiments here recorded represent the work of many observers in many countries, carried on with different subjects under a great variety of conditions. The results have been before the world for about twelve years, and during that period have been subjected to much adverse and some instructive criticism. But no alternative explanation which has yet been suggested has attained even a momentary plausibility.