24 NATURAL HISTORY. 



but not rightly : for that were to make every casting 

 of the skin a new birth : and besides, the secundine is 

 but a general cover, not shaped according to the parts ; 

 but the skin is shaped according to the parts. The 

 creatures that cast their skin are, the snake, the viper, 

 the grasshopper, the lizard, the silk-worm, &c. Those 

 that cast their shell are, the lobster, the crab, the era- 

 fish, the hodmandod l or dodman, the tortoise, &c. 

 The old skins are found, but the old shells never : so 

 as it is like they scale off and crumble away by de 

 grees. And they are known by the extreme tender 

 ness and softness of the new shell, and sometimes by 

 the freshness of the colour of it. The cause of the 

 casting of skin and shell should seem to be, the great 

 quantity of matter in those creatures that is fit to mak^ 

 skin or shell ; and again, the looseness of the skin or 

 shell, that sticketh not close to the flesh. For it is 

 certain that it is the new skin or shell that putteth 

 off the old : so we see that in deer it is the young 

 horn that putteth off the old ; and in birds, the young 

 feathers put off the old : and so birds that have much 

 matter for their beak, cast their beaks ; the new beak 

 putting off the old. 



1 Shell snail. But of course neither they nor tortoises change their 

 shells. It would be endless to point out all similar inaccuracies. Thus, 

 a little further on, it is said that in deer the new horn puts off the old, 

 whereas it is quite clear that the growth of the new horn does not begin 

 until the old one is shed; it goes on, in fact, under the skin which some 

 time afterwards forms over what may be called the stump. This is suffi 

 ciently obvious; but there is probably an equal error, though not so easily 

 detected, in what is said with respect to feathers. The truth is, that the 

 habit of close observation of common phenomena does not appear to have 

 been much developed by Bacon s way of life. 



