CHAP, ix Nutrition of Heterotrophic Plants 433 



vations made by Pasteur in 1860 and 1862, by Naegeli 

 in 1879 and 1882, by Reinke in 1883, showed that Fungi 

 are capable of feeding upon a great variety of carbon 

 compounds, some fairly simple, others extremely complex, 

 and Pasteur especially showed in his classical researches 

 on racemic acid that they exercise a certain selective 

 power. It would take us far beyond the limits of our 

 present studies to attempt to give a resume of the researches 

 made during the later years of the century into the various 

 food materials Fungi are capable of utilizing. We must, 

 however, call attention to the discovery that they carry 

 out digestive processes in the bodies of their hosts, or in 

 the dead organic matter in which they live, by means of 

 enzymes identical with those which have been found in 

 the higher plants. Much of our knowledge on this point 

 has been due to the work of Bourquelot and his pupils, 

 to which reference has already been made. 



This mode of nutrition was ascertained to be characteristic 

 of certain parts of the higher green plants. Van 

 Tieghem called attention to the feeding of the embryo at 

 the expense of the endosperm, and showed that the latter 

 can be replaced by an artificial preparation of carbo- 

 hydrates and proteins. The nutrition of the pollen-tube in 

 its passage down the style was studied by Correns in 1889, 

 by Molisch in 1893, and by the present writer in the same 

 year, and was found to be completely in accord with the 

 nutrition of the Fungi. Beijerinck in 1890 showed that 

 certain lichen-algae prefer peptone to any other form of 

 combined nitrogen. 



But some very striking exceptions to the ordinary mode 

 of life gradually became known. Researches, to which we 

 must refer in detail, showed that various green plants living 

 under exceptional conditions, are capable of feeding on 

 the bodies of insects, after a preliminary process of either 

 digestion or putrefaction ; while both fungi and bacteria were 



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