310 THE ZOOLOGIST. 



first learnt from Europeans to eat Oysters.* The Australians do 

 not, however, eat everything indiscriminately, but reject several 

 things eaten by Europeans, as certain fish, crustaceans, or fungi; 

 yet they feel no disgust at such things as maggots or rotten 

 eggs, or even the contents of the intestines of animals taken in 

 hunting.! 



Plants can also vary the nutrient salts they absorb according 

 to the supply of the same. In the yew (Taxus baccata) there is 

 frequently a replacement of calcium by magnesium. On com- 

 paring the quantities of calcium and magnesium in the ash of 

 yews grown on lime and on gneiss, respectively, with those 

 yielded in the case of serpentine formation, we find that magnesia 

 preponderates considerably in weight over lime in a yew from 

 serpentine rocks (which are in the main a compound of magnesia 

 and silicic acid), whilst the proportion between these two salts is 

 reversed in a yew grown upon limestone. The obvious inference 

 from the table is that, in plants from a serpentine ground, lime 

 is to a great extent replaced by magnesia.! 



Among other vagaries in animal diet may be mentioned that 

 of Snails, who also devour insects, particularly Coleoptera.§ On 

 the other hand, the operation is sometimes reversed. M. Flaminio 

 Baudi found Cychrus cyclindricollis feeding on the body of Helix 

 frigida ; || and Mr. Trovey Blackmore had observed Carabus 

 stenocephalus to feed on the abundant Snails in Morocco. 



Such facts as these tend to prove that a fauna is not happy 

 by having no history, as is so often and so easily imagined ; but 

 rather that its history is like that of a continental humanity — one 

 series of wars, attack not on all sides at once, but ever recurring 

 from one quarter or another. The friend of to-day may have 

 been the enemy of a long ago. Environmental changes may have 

 produced, by a scarcity of usual food, a change of diet, and then 

 a race of animals hitherto enjoying a comparative immunity from 

 attack may suddenly become almost annihilated by unexpected 

 foes. Thus we may now find an inherited mimetic resemblance 



* Ratzel, ' History of Mankind,' vol. i. p. 337. f Ibid. p. 361. 



j Kerner and Oliver, ' Nat. Hist, of Plants,' vol. i. p. 70. 

 § Cf. Wollaston and other observers, « Zoologist,' vol. i. p. 201 ; vol. iii. 

 pp. 943, 1035, 1038. 



|| ' Petites Nouvelles Entomologiques.' 



