Note 92 — THE INDIVIDUAL ORGANISM WITH REGARD TO FORM AND METABOLISM (continued 3)

I should think that the problem of the re-establishment of irritability, in principle at least, arises even when there is not a trace of so-called “fatigue” or of a “refractory period.” The process of restoring may be so rapid as not to be noticeable, nevertheless some sort of restoring is to be postulated. We may say the “irritability” of an elastic ball is re-established by its elasticity. A certain analogy to this case may perhaps be found in the muscle. But the irritability of nerves with respect to nervous conduction, and of glands with respect to secretion, or of the articulations of Mimosa may be well understood, hypothetically at least, if we assume that the ordinary course of metabolic events is apt in itself to lead to a certain state or condition of the organs in question upon which their irritability is based. Certain general conditions of functioning, as for instance the presence of oxygen for the contraction of the muscle, would better be looked upon as necessary “means” of functioning than as being part of irritability as such. “Fatigue,” of course, may also be due to the absence of such “means” or to abnormal conditions originated by functioning itself.