Such a statement, of course, does not say that all metabolism has proved to be of a chemical nature: the *action* of the ferment when produced is chemical, but we do not know at all *how* the ferment is produced; we only know that a high degree of active regulation is shown in this production. In fact, it has been proved in some cases, and probably will be proved in a great many more in the near future, that all metabolic ferments, whether they promote oxidation or assimilation proper or chemical decomposition, are produced in a regulatory manner with regard to the specific compound to be dissociated or to be built up. In this way the whole field of metabolism is really covered by “regulations.” Are they real “secondary” ones? Of course the regulatory correspondence applies to the process of *secretion* in the *first* place, not to the actual formation of the ferment inside the cell. The correspondence as to secretion, no doubt, is of the primary type; is there any secondary regulation with regard to the real *production* of the ferment? I am sorry that I cannot answer this question affirmatively. Nothing is *known* at present, even here, that really proves the existence of adaptation of the secondary type: there *might* be a sort of statical “harmony” at the base of it all, established before all functioning *for* functioning.[108] [108] Compare the excellent review of the subject by Bayliss and Starling in the *Ergebnisse der Physiologie*, 5, 1906, p. 664. The reader who misses here an analysis of the brilliant discoveries of Pawlow and his followers, relating to so-called “psychical and associative secretion,” will find these facts dealt with in another section of the book. These facts, indeed, would prove vitalism, it seems to me. The only facts of secondary metabolic regulations which are known at present have been found in combination with phenomena of restitution after real disturbances of organisation, where, indeed, numbers and numbers of regulatory changes of metabolism, both in animals and plants, have also been recorded. But there is not one case of a secondary regulation really known to affect pure metabolism alone.[109] This is a new indicium of the primacy of *form* in the organism. [109] It would be a true secondary metabolic regulation, if after the extirpation of one gland another different one were to assume its function. Nothing is known in this respect except a few rather doubtful observations about the interchange of functions between thymus and thyroid, except also the fact that the so-called lymph-glands increase in size after the extirpation of the spleen. Even here, of course, a sort of “restitution” would be included in adaptation proper. IMMUNITY THE ONLY TYPE OF A SECONDARY PHYSIOLOGICAL ADAPTATION