WITH THE DOMAIN OF THE INORGANIC 61 



is adapted to put on a garment of invisibility against cer- 

 tain backgrounds; the hedgehog is adapted to meet the win- 

 ter by hibernation; the peacock is adapted to captivate the 

 peahen; the mother mammal is delicately adapted for the 

 prolonged ante-natal life of the offspring; and the so-called 

 ^ egg-tooth ' at the end of a young bird's bill is adapted to 

 the single operation of breaking the egg-shell — and so on 

 throughout the whole animal kingdom, for the point of this 

 random list is but to remind us that (with a few very inter- 

 esting exceptions) every detail of structure and function 

 may be regarded as adaptive. As the late Professor Weis- 

 mann used to say, '^ When you take away all the adapta- 

 tions from a whale, there is not much left." To illustrate 

 subtlety, however, let us pause for a moment over a partic- 

 ular case. 



The illustration we select concerns the parental care in 

 a remarkable 'New Guinea fish called Kurtus. Each egg 

 has an envelope of over a hundred twisted threads, coiled 

 like the rubber filaments in a cored golf-ball. When the 

 eggs are laid the filaments unwind automatically and unite 

 in strings, which combine into a cylindrical cord. Thus the 

 eggs are bound together, forming a tw^in cluster like a 

 double bunch of onions such as we see the Breton boys carry- 

 ing in the streets. But what is the bunch to be fastened to ? 

 The answer is almost incredible. At the breeding season, 

 Prof. Max Weber tells us, a bony process on the top of the 

 skull of the male fish grows forwards and downwards like 

 a bent little finger, and forms eventually a ring or ' eye '. 

 But before the hook becomes an eye the cord of the double 

 bunch of eggs is somehow passed into the loop and attached, 

 and the male fish goes about with his prospective family 

 fastened to the top of his head. The female shows no trace 



