convey no ‘bound’ energy, only free energy capable of discharge. In my opinion, however, it is better for the present to express oneself as to these conditions in the least committal way. At any rate by these speculations we should have brought the origin of consciousness into a certain connection with the position of the system Bw. and with the peculiarities of the excitation process to be ascribed to this. We have more to say about the living vesicle with its receptive outer layer. This morsel of living substance floats about in an outer world which is charged with the most potent energies, and it would be destroyed by the operation of the stimuli proceeding from this world if it were not furnished with a protection against stimulation (_Reizschutz_). It acquires this through its outermost layer—which gives the structure that belongs to living matter—becoming in a measure inorganic, and this now operates as a special integument or membrane that keeps off the stimuli, i. e. makes it impossible for the energies of the outer world to act with more than a fragment of their intensity on the layers immediately below which have preserved their vitality. These are now able under cover of the protecting layer to devote themselves to the reception of those stimulus masses that have been let through. But the outer layer has by its own death secured all the deeper layers from a like fate—at least so long as no stimuli present themselves of such a strength as to break through the protective barrier. For the living organism protection against stimuli is almost a more important task than reception of stimuli; the protective barrier is equipped with its own store of energy and must above all endeavour to protect the special forms of energy-transformations going on within itself from the equalising and therefore destructive influence of the enormous energies at work in the outer world. The reception of stimuli serves above all the purpose of collecting information about the direction and nature of the external stimuli, and for that it must suffice to take little samples of the outer world, to taste it, so to speak, in small quantities. In highly developed organisms the receptive external layer of what was once a vesicle has long been withdrawn into the depths of the body, but portions of it have been left on the surface immediately beneath the common protective barrier. These portions form the sense organs, which essentially comprise arrangements for the reception of specific stimuli, but also possess special arrangements adapted for a fresh protection against an overwhelming amount of stimulus, and for warding off unsuitable kinds of stimuli. It is characteristic of them that they assimilate only very small quantities of the outer stimulus, and take in only samples of the outer world; one might compare them to antennae which touch at the outer world and then constantly withdraw from it again.