V] OF THE CILIATE INFUSORIA 425 



of the body and very especially in the said gullet or re-entrant 

 portion of the surface. Now we have seen the nodoid to be a curved 

 surface, re-entering on itself and endless; no method of support, 

 by wire-rings or otherwise, enables us to construct or reahse more 

 than a small portion of it. But the typical cihate, such as Para- 

 moecium, looks just hke what we might expect a^ nodoid surface to 

 be, if we could only realise it (or a single segment of it) in a drop of 

 fluid, and imagine it to be kept in quasi-equiUbrium by continual 

 cihary activity. I suspect, indeed, that here is nothing more, and* 

 nothing less, than a partial realisation of the nodoid itself; that the 

 so-called gullet is but the characteristic inversion or "kink" in that 

 curve; and that the ciHa, which normally clothe the surface and 

 always line the gullet, are needed to reahse and to maintain the 

 unstable equihbrium of the figure. If this be so — it is a suggestion 

 and no more — we shall have found among our simple organisms the 

 complete realisation, in varying abundance, of each and all of the 

 six surfaces of Plateau. On each and all of them we have a host 

 of beautiful "patterns" of various sorts; all of them so beautiful 

 and so symmetrical that they ought to be capable of geometric 

 representation — and all waiting for their interpreter ! 



From all these configurations, which the law of minimal area 

 controls and dominates, Aynoeba stands aloof and alone. The rest 

 are all figures of equilibrium, unstable though it may sometimes be. 

 But Amoeba is the characteristic case of a fluid surface without an 

 equihbrium; it is the very negation of stabihty. In composition 

 it is neither constant nor homogeneous ; its chemistry is in constant 

 flux, its surface energies vary from here to there, its fluid substance 

 is drawn hither and thither; within and without it is never still, 

 be its motions swift or be they slow. The heterogeneity of its 

 system points towards a maximal surface-area, .rather than a 

 minimal one ; only here and there, in small portions of its hetero- 

 geneous substance, do we see the rounded contours of a fluid drop, 

 in token of temporary equihbrium. Only when its heterogeneous 

 reactions quieten down and the little living speck enters on its 

 "resting-stage," does the protoplasmic body withdraw itself into a 

 sphere and the law of area minima come into its own. Physically 

 analogous is the case of such comphcated pseudopodia, or " axopodia ", 

 as we find among the Foraminifera and Hehozoa : where the whole 



