THE CYCLE OF LIFE 393 



matic illustration may be found in the story of Neptune's 

 Cup. This huge cup-like sponge (Poterion neftuni or 

 Cliona patera) may grow to an immense size — a cup that 

 only a god could drain. It may be a couple of feet in 

 height. Now Vosmaer discovered what Topsent has con- 

 firmed, that this huge cup is the free form of a small boring 

 sponge which is found making gimlet-hke holes in shells. 

 There are also free and prisoner forms of the common 

 Cliona celata. 



Growth. — ^The power of growth is one of the insignia of 

 life. It is characteristic of all hving creatures, and every one 

 knows in a practical way what it means, though a precise 

 definition is not easy. One may say that growth is increase 

 in the size or volume of an organism, and usually imphes 

 increase in mass or weight. But there is evidently no 

 small difierence between an increase of size due to a sub- 

 cutaneous deposit of fat, such as we see in prize pigs and 

 prize fat cattle, and the slow continuous growth of a lean 

 fish hke a haddock. There is a marked difference between 

 an enlargement due to the accumulation of watery fluid 

 and the fine growth of an embryo's brain. It is not growth 

 that we see when a parched turnip or the hke is surrounded 

 with water and expands, or when a frog, leaving its winter- 

 quarters in the mud, plunges into the pond, and, absorbing 

 water through its skin, may be watched ' swelhng visibly '. 

 It seems, indeed, that more than one word is required 

 to cover the various phenomena which may be quite 

 reasonably referred to as growth. 



We cannot speak of growth as one of the characteristics 

 of hving organisms without remembering that the power 

 of growth under suitable conditions is also the fundamental 

 property of crystals. Since Professor Lehmann pubhshed 



