298 SCIENTIFIC ILLUSTRATIONS [Rec 



apes with a stick, or takes the cat's-paw, if the story be true, to 

 extract chestnuts from the fire ; in the fox, who spreads cods' 

 heads as a bait to catch gulls, or immerses himself in the water, 

 and holds a bough over his head to deceive the hunters ; in the 

 racoon, who captures deer with pieces of moss; in the bear, 

 who, as told in the account of Cook's third voyage, rolls down 

 pieces of rock to crush stags; in the rat when he leads his 

 blind brother with a stick ; in the bee which uses ]!fropolis to 

 cover a slug that has died in the hive ; in the spider, which 

 attaches a piece of wood to its web to steady it ; and in the 

 nymph of water-moths, which select straws in which they 

 may float, putting in a bit of wood if it be too heavy, or a bit 

 of gravel if it be too light. Indeed it has been said that there 

 is nothing that man effects with all his tools, and all his skill 

 in the use of them, of which some indication may not be seen 

 in the brute or the insect. Thus the beaver and the bee give 

 examples of construction, the spider of weaving, and the little 

 nautilus of sailing. "Who taught the raven in a drought" 

 (asks Bacon in his Advancement of Learning) " to throw pebbles 

 into a hollow tree where she espieth water, that the water 

 might rise so as she might come to it ? " It is a fact that the 

 raven when she sees water that she cannot reach seems to con- 

 sider and find out means for bringing it within her reach. She 

 finds herself necessitated to raise it to a certain limit, and she 

 does so by putting pebbles into it. And her mode of proceed- 

 ing appears to us as much the result of reason (though of 

 a lower degree of exercise of it) as man's invention of the 

 pump. R. 



Reciprocity a law of Nature. 



When all the arguments of free-traders and of protectionists 

 are ended, the scientific man is delighted to be able to invite 

 the student to hear what Nature has to say on the question of 

 reciprocity. One lesson is enough to pour on it a flood of 

 light sufficient to settle all further debate. It is that of the 

 plants and animals in relation to the atmosphere. Let us in- 

 vestigate the matter attentively. Plants possess two modes of 

 respiration : one diurnal, in which the leaves absorb the car- 

 bonic acid of the air, decompose this gas, and extract the oxygen 



