THE “MORPHAESTHESIA” OF NOLL[69]
We may briefly mention that group of botanical phenomena, by which the botanist Noll has been led to the concept of what he calls “morphaesthesia,” or the “feeling” for form; a concept, the full discussion of which would lead to almost the same conclusions as our analysis of the harmonious systems has done. In the Siphoneae, a well-known order of marine algae with a very complicated organisation as to their exterior form, the protoplasm which contains the nuclei is in a constant state of circulation round the whole body, the latter not being divided by proper cell-walls. On account of this constant movement it is certainly impossible to refer morphogenetic localisation to definite performances of the nuclei. Nor can any sort of structure in the outer protoplasmic layer, which is fixed, be responsible for it, for there is no such structure there: hence there must be a sort of feeling on the part of the plant for its relative body localities, and on account of this feeling morphogenesis occurs. This “feeling” is styled “morphaesthesia” by Noll, and to it he tries to refer all sorts of different botanical form-phenomena,[70] for instance what is called “autotropism,” that is, the fact that branches of plants always try to reassume their proper angle with regard to their orientation on the main axis, if this orientation has been disturbed. It may be an open question if this particular application of the theory is right: certainly there seems to be much truth in the establishment of the concept of morphaesthesia, and we only have to object to its psychological name. But that may be done in a more general form on a later occasion.
RESTITUTIONS OF THE SECOND ORDER
In the hydroid polyp Tubularia, already familiar to us as being a most typical representative of the harmonious-equipotential systems, a very interesting phenomenon has been discovered[71], almost unparalleled at present but nevertheless of a general importance, a phenomenon that we may call a restitution of a restitution, or a restitution of the second order. You know that the first appearance of the new head of Tubularia, after an operation, consists in the formation of two rings of red lines, inside the stem, these rings being the primordia of the new tentacles. I removed the terminal ring by a second operation soon after it had arisen, disturbing in this way the process of restitution itself: and then the process of restitution itself became regulated. The organism indeed changed its course of morphogenesis, which was serving the purposes of a restitution, in order to attain its purpose in spite of the new disturbance which had occurred. For instance, it sometimes formed two rings out of the one that was left to it, or it behaved in a different way. As this difference of morphogenetic procedure is a problem by itself, to be discussed farther on, we shall postpone a fuller description of this case of a restitution of the second degree.
At present I do not see any way of proving independently the autonomy of life by a discussion of these phenomena; their analysis, I think, would again lead us to our problem of localisation and to nothing else; at least in such an exact form of reasoning as we demand.
ON THE “EQUIFINALITY” OF RESTITUTIONS[72]
I have told you already that Tubularia in the phenomena of the regulation of restitutions offers us a second problem of a great general importance, the problem of the Equifinality of Restitutions. There indeed may occur restitutions, starting from one and the same initial state and leading to one and the same end, but using very different means, following very different ways in the different individuals of one and the same species, taken from the same locality, or even colony.
Imagine that you have a piece of paper before you and wish to sketch a landscape. After drawing for some time you notice that you have miscalculated the scale with regard to the size of the paper, and that it will not be possible to bring upon the paper the whole of the landscape you want. What then can you do? You either may finish what you have begun to draw, and may afterwards carefully join a new piece of paper to the original one and use that for the rest of the drawing; or you may rub out all you have drawn and begin drawing to a new scale; or lastly, instead of continuing as you began, or erasing altogether, you may compromise as best you can by drawing here, and erasing there, and so you may complete the sketch by changing a little, according to your fancy, the proportions as they exist in nature.
This is precisely analogous to the behaviour of our Tubularia. Tubularia also may behave in three different ways, if, as I described to you, the terminal one of its two newly arisen rings of tentacle primordia is removed again. It may complete what is left, say the basal tentacle ring, then put forth from the horny skeleton (the “perisarc”) the new head as far as it is ready, and finally complete this head by a regular process of budding regeneration. But it also may behave differently. It may “erase” by a process of retro-differentiation all that has been left of what had already been formed, and then may form de novo the totality of the primordia of a new head. Or, lastly, it may remove a part of the middle of the one ring of tentacle rudiments which was left, and may use this one ring for the formation of two, which, of course, will not be quite in the normal relations of place with regard to each other and to the whole, but will be regulated afterwards by processes of growth. Thus, indeed, there is a sort of equifinality of restitution: one starting-point, one end, but three different means and ways.