THE METABOLISM OF PLANTS. I? I 



which yield glucose as one of the products of their decompo- 

 sition ; these may be either non-nitrogenous (e.g. digitalin) 

 or nitrogenous (e.g. amygdalin). Starch and oil are also the 

 forms in which the non-nitrogenous reserve-materials are 

 most commonly stored up in -other depositories : thus starch 

 is to be found in the winter in the cells of the ground-tissue 

 of perennial roots and rhizomes, of the trunks of trees, also 

 in the septate and unseptate fibres and in the parenchy- 

 matous cells of the wood of the stems of Dicotyledons 

 (Sanio) so long as these cells contain protoplasm, in bulbs 

 and corms ; oil occurs in some fruits, such as the Olive, and 

 in the spores of many Fungi. In certain cases, however, 

 carbohydrate is stored up in other forms ; in the root of the 

 Beet it is present as cane-sugar ; in the bulb of the Onion 

 and in many fruits as glucose ; in the tuberous roots of the 

 Dahlia as inulin ; glycogen has been found by Errera in 

 various Ascomycetous Fungi, especially in their asci, and by 

 Reinke in the plasmodium of ^Ethalium ; mannite has been 

 found to be commonly present in Agarics by Miintz, and 

 many of these Fungi contain a form of sugar known as 

 trehalose ; mannite has also been found by de Luca in the 

 leaves, flowers, and unripe fruits of the Olive, and in various 

 parts of a great number of plants ; the dried juice (manna) 

 obtained from Fraxinus Ornus consists principally of mannite. 

 The proteid reserve-materials are not known to be deposited 

 in the form of aleurone-grains in any other organs besides 

 seeds, but crystalloids have been found free in the cells of 

 various plants, for example, in the peripheral cells of the 

 potato-tuber (Bailey), in the nuclei of the epidermal cells of 

 the integument of the ovule of Lathrcea squamaria (Radlkofer), 

 in the cells of the Florideae (Cramer, Klein), in the mycelium 

 of the Mucorini (Klein, van Tieghem). Amides have been 

 found stored up in roots and tubers. Schulze and Urich 

 found glutamin in Beet-roots, and Scheibler found asparagin 

 and a substance termed betai'n ; it appears that in some 

 years glutamin, in others asparagin is the more abundant. 

 In potatoes Schulze and Barbieri found asparagin, leucin and 

 tyrosin. 



