(Aside...)

In conclusion, it is evident that the system A, B, M could be extended to a three dimensional system. [However] it is judged that the implementation of a three dimensional model would involve difficulties which are not worth overcoming at this stage, as the extension of the proposed model to three dimensions would not involve any conceptual modifications. [Handwritten] In the three dimensional model the motion of the @ and M- particles would take place in a three dimensional space. The chains of M* [particles] would now become surfaces, with edges composed of M+ [particles] capable of ``capturing'' new M- [particles] allowing the surface to grow and close, enclosing the @ particle. The volume inside this ``spherical-membrane'' would become populated by M- particles, ready to repair the ``membrane'' at the points where it is destroyed [disrupted?] by disintegration of the M* particles.

-Varela & Maturana Protobio 1971 (?)