440 NATURE AND MAN. 



home, successive generations came to adapt themselves to greater 

 and yet greater degrees of winter cold, — the question still recurs, 

 whence this ancestral adaptability ? 



The influence of physical conditions in modifying the con- 

 stitution is well known to be most strongly exerted during the 

 earlier period of life ; for as long as the organism is in process of 

 development, it will grow to its environment, as it will not do at 

 a later epoch, when it will either resist or succumb. We are told 

 by Sir Charles Lyell that the Cornish miners who went out some 

 sixty years ago to work the Real del Monte mines in Mexico, took 

 out some greyhounds to hunt the hares which abound on the 

 elevated plateaux of that country ; but that, in consequence of 

 the rarefied condition of the air, the dogs could not continue the 

 chase, but lay down panting for breath. The offspring of those 

 dogs, however, brought up at this elevation, were able to run down 

 the hares as well as if both had been on a lower level. The con- 

 stitution of the young dogs adapted itself to the environment in 

 which they grew up ; but whence that adaptability ? We do not 

 find it in any but living organisjtis ; no physical property gives the 

 least account of it. 



The most remarkable example with which I am acquainted, of 

 the effect of physical conditions in modifying the developmental 

 process, is that which is seen in the economy of the Hive-bee. It 

 is well known that whenever, from any cause, a community wants 

 a queen, a worker-grub at an early stage is selected : a " royal 

 cell " is constructed round it, several ordinary cells being de- 

 molished for the purpose, and their contained grubs killed ; the 

 selected grub is fed with " royal jelly " instead of with " bee- 

 bread;" and (it seems probable) a higher temperature is main- 

 tained by the incessant activity of the bees which cluster about 

 the royal nursery. In due time a perfect " queen " comes forth, 

 differing from the " worker " not merely in the completeness of its 

 reproductive apparatus, but in the conformation of its jaws and 

 antennae, the absence of " pollen-baskets " on the thighs, and yet 

 more remarkably in its instincts. Now it is obviously no ex- 

 planation of this extraordinary transformation to say that every 

 worker grub is a " potential " queen ; because the attributing this 

 " potentiality " to it is only another way of expressing the fact 



