Chap, in.] VEGETAL ASSIMILATION AND DIS-ASSIMILATION. 117 



deep, is covered with organized beings, all belonging to the group 

 of the Protozoa of Hseckel. This bottom is everywhere car- 

 peted with those little sarcodic, gelatinous, contractile organ- 

 isms, called by Huxley Bathybius Hcechelii. Amongst these 

 bathybians live foraminifers, rhizopods, radiolites, sponges.' 



We therefore must admit that certain of these rudimentary 

 animal organisms can decompose water, carbonic acid, and 

 ammonia, or assimilate the numerous, organic detritus in suspen- 

 sion in the marine waters, arising from the dejections of animals, 

 and from the decomposition of their dead bodies. It is only thus 

 that they can live, can multiply, and can aliment more complex 

 animals. 



Analogous facts have been observed by MM. de Candolle, 

 Forel, and Dufour, in the Lake of Geneva. There also the most 

 sensitive photographic paper ceases to take an impression beyond 

 the small depth of 50 or 60 metres in summer, and 40 or 60 in 

 winter. Nevertheless, at the bottom of the lake live from 

 thirty-five to forty species of lower animals. 



The idea of a necessary solidarity between the two organic 

 kingdoms must then be abandoned. This solidarity only exists, 

 in a very large measure, in the organized terrestrial world. 

 There, we may admit, as a general thesis, that the vegetal 

 kingdom is necessary to the animal kingdom. Now nearly the 

 whole of plants cannot live without light. But the calorific and 

 chemical solar rays are not less necessary to the maintenance of 

 life. Solar irradiation is then one of the grand causes of the 

 production, development, and duration of organized beings. The 

 great theory of the transmutation and correlation of physical 

 forces is therefore applicable to biology. We must guard, 

 however, against making this application with a mathematical 

 and inflexible rigour which the subject does not allow of. We 

 think also that there has been too great an inclination of late 

 years to consider solar irradiation as the unique and universal 



1 The Depths of the Sea, by C. Wyville Thomson. 8yo. LondoD, 1873. 

 French Trantlation ; Les Abtmes de la Mer, Svo. Paris, 1875. 



