So it is important to note that the living substance is only slightly accessible for scientific investigation without it becoming disturbed and with it destroyed, and thus then being not living substance at all anymore, but a declined state, whose investigation only reveals the properties of this state. The "outside", not being a living state, cannot reveal anything. In attempting to get hold of the "inside", it directly transforms (because it necessarily has to) into "outside" and is then no life anymore.
The within an atomic range (despite the often large striking volume) possible quantum mechanical effect of a change or killing of the living substance, as a result of photon irradiation or poisonous molecules, is a sort of minimal effect which is greatly surpassed by every other executable (except mental) experimental intervention, and thus -- with correspondingly hefty states of affairs in ionizing irradiation -- always forcing us to choose between a reaction not revealing anything [irradiation too weak], or a result-refusing (excluding) "killing" of the unimolecular whole [irradiation stronger].
The "corpuscular" research in the organismic domain (micro-preparation and micro-dying, light and electron microscopy) may be intensified still further, but the range cannot be extended farther "down" anymore, because then, unavoidably, the effects of "complementarity" already exclude further knowledge [Müller may mean here that the means of research then become too physical and with it the results.]. Investigation essentially must proceed further with pencil and paper and with the wit of mind as an instrument.