LECTURE XXIII. 



THE ABSORPTION OF ORGANIC NUTRITIVE MATERIAL. PARA- 

 SITES. COPROPHYTES (SAPROPHYTES). INSECTIVOROUS 

 PLANTS. 



All that has hitherto been said on the nutrition of plants has been with refer- 

 ence immediately only to those which are provided with abundance of chlorophyll, 

 and the land-plants provided with large transpiration surfaces were placed especially 

 in the foreground as the typical chlorophyll-plants, in which all the chemical and 

 mechanical processes of nutrition are called into play. As to the nutrition of these 

 normal plants, two chief points were noticed : first, the formation of new organs 

 takes place at the expense of the reserve-materials which have been produced by 

 the mother-plant and stored up in the reservoirs of reserve-material ; after these 

 materials have been consumed, or, as we may also say, at the conclusion of ger- 

 mination, the second period of nutrition begins, the assimilation of organic plant- 

 substance by the decomposition of the atmospheric carbon dioxide in the organs 

 containing chlorophyll, under the influence of light. 



There are, however, numerous plants which are entirely devoid of chloro- 

 phyll, or which possess so little of it that it is scarcely of any importance in 

 nutrition. Since now the decomposition of carbon dioxide ; and the resulting 

 formation of organic plant-substance are effected exclusively by means of the chlo- 

 rophyll, it follows at once that all the plants of this second section are incapable 

 of exercising the nutritive activity which is characterised by assimilation. Plants 

 devoid of chlorophyll exist during their whole life in a condition which cor- 

 responds to the germination of normal plants : like the seedlings of seeds which 

 contain endosperm, like the germinal shoots of tubers, bulbs and root-stocks, and like 

 the unfolding winter-buds of trees, plants devoid of chlorophyll take up the whole of 

 their food for the purpose of growth directly, in the form of organic compounds 

 of already-formed vegetable substance. They do not produce organic compounds 

 containing carbon, but they absorb them, and change them in accordance with the 

 purposes of their own growth. 



On the whole, it is practically the same whether the plants devoid of chlorophyll 

 absorb their organic nutritive matters from other living plants or living animals, or 

 whether they make use of the dead bodies of plants and animals or their dissolved 

 constituents for their nutrition. In the first case they are distinguished as Parasites, in 



