Bionomics. 193 



impressed him as being "full of truth", although "with 

 some little nonsense". And at last Sprengel's work 

 had its reward. 



Of much importance in the understanding of the 

 relations between large sets of organisms living in the 

 same area, is the occurrence of what may Nutritive 

 be called "nutritive chains". As Prof. O. Chains. 

 Zacharias points out, some of the fresh-water fishes in 

 a pond depend upon the supply of small crustaceans 

 (copepods, &c.), and these again on much minuter 

 organisms (infusorians, diatoms, &c.), and these again, 

 to some extent, on the bacteria which cause the putre- 

 faction of the dead organic matter. In short, there is 

 a circulation of matter from one level of life to another. 



Dr. Bernhard Fischer has shown that even on the 

 high-seas bacteria are present, playing their usual part 

 of "middlemen between death and life" by transform- 

 ing dead organic matter into inorganic substances 

 which can be used again by plants. As far as is known 

 they are absent from the ice-cold water on the floor of 

 the ocean. 



Prof. W. C. M'Intosh and Mr. George Murray have 

 given definiteness to the conclusion that "all fish is 

 diatom" in the same physiological sense as "all flesh 

 is grass ". The food-canals of the copepods, and other 

 small crustaceans which form a large part of the food 

 of fishes, contain abundant remains of the siliceous 

 shells of diatoms. 



There is not a more fascinating chapter in bionomics 

 than that which deals with the inter-relations of plants 

 and animals. We refer to their complemen- 

 tary relations as regards interchange of tions "between 

 gases with the atmosphere ; the ultimate j^mais"* 

 dependence of animal -life upon plant -life, 

 since only plants can subsist upon inorganic food; the 

 selective action of animals on plants, which Prof. Stahl 

 has worked out in the case of snails; the selective 

 action of bacteria on animals, which Prof. Haycraft 

 has skilfully dealt with in connection with man; the 

 carnivorous plants, which have fascinated many from 

 Linnaeus to Darwin; the whole question of the pollina- 



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