V] THE SHAPE OF A SPLASH 239 



glass-blower can make most things that the potter makes, by 

 cutting oft' 'portions of his hollow ware. And besides, when this 

 fails, and the glass-blower, ceasing to blow, begins to use his rod 

 to trim the sides or turn the edges of wineglass or of beaker, he 

 is merely borrowing a trick from the craft of the potter. 



It would be venturesome indeed to extend our comparison 

 with these liquid surface-tension phenomena from the cup or 

 calycle of the hydrozoon to the little hydroid polype within : and 

 yet I feel convinced that there is something to be learned by such 

 a comparison, though not without much detailed consideration 

 and mathematical study of the surfaces concerned. The cylin- 

 drical body of the tiny polype, the jet-like row of tentacles, the 

 beaded annulations which these tentacles exhibit, the web-like 

 film which sometimes (when they stand a little way apart) conjoins 

 their bases, the thin annular film of tissue which surrounds the 

 little organism's mouth, and the manner in which this annular 

 "peristome" contracts*, like a shrinking soap-bubble, to close the 

 aperture, are every one of them features to which we may find 

 a singular and striking parallel in the surface-tension phenomena 

 which Mr Worthington has illustrated and demonstrated in the 

 case of the splash. 



Here however, we may freely confess that we are for the 

 present on the uncertain ground of suggestion and conjecture; 

 and so must we remain, in regard to many other simple and 

 symmetrical organic forms, until their form and dynamical 

 stability shall have been investigated by the mathematician : in 

 other words, until the mathematicians shall have become persuaded 

 that there is an immense unworked field wherein they may labour, 

 in the detailed study of organic form. 



According to Plateau, the viscidity of the liquid, while it 

 helps to retard the breaking up of the cyhnder and so increases 

 the length of the segments beyond that which theory demands, 

 has nevertheless less influence in this direction than we might 

 have expected. On the other hand, any external support or 

 adhesion, such as contact with a solid body, will be equivalent to 

 a reduction of surface-tension and so will very greatly increase the 

 * See a Study of Splashes, p. 54. 



