318 MAGNALIA NATURE: OR THE GREATER 



morphologist as well as the physiologist may draw important 

 consequences. 



It was Hofmeister who first showed, more than forty 

 years ago, that when any drop of protoplasm, either over all 

 its surface or at some free end (as at the tip of the pseudo- 

 podium of an amoeba), is seen to ' round itself off,' that is not 

 the effect of physiological or vital contractility, but is a 

 simple consequence of surface tension, of the law of the 

 minimal surface ; and on the physiological side, Engelmann, 

 Biitschli and others have gone far in their development of 

 the idea. Plateau, I think, was the first to show that the 

 myriad sticky drops or beads upon the weft of a spider's web, 

 their form, their size, their distance apart, and the presence 

 of the tiny intermediate drops between, were in every detail 

 explicable as the result of surface-tension, through the law 

 of minimal surface and through the corollary to it which 

 defines the limits of stability of the cylinder ; and, accord- 

 ingly, that with their production, the will or effort or intel- 

 ligence of the spider had nothing to do. The beaded form 

 of a long, thin, pseudopodium, for instance of a Heliozoan, is 

 an identical phenomenon. It was Errera who first conceived 

 the idea that not only the naked surface of the cell, but the 

 contiguous surfaces of two naked cells, or the delicate incipient 

 cell-membrane or cell-wall between, might be regarded as a 

 weightless film, whose position and form were assumed in 

 obedience to surface-tension. And it was he who first showed 

 that the symmetrical forms of the unicellular and simpler 

 multicellular organisms, up to the point where the develop- 

 ment of a skeleton complicates the case, were one and all 

 identical with the plane, sphere, cylinder, unduloid and cate- 

 noid, or with combinations of these. Berthold and Errera 

 almost simultaneously showed (the former in far the greater 

 detail), that in a plant each new cell-partition follows the 

 law of minimal surface, and tends (according to another law 

 which I have not particularised) to set itself at right angles 



