TRANSLOCATION OF ORGANIC FOOD-SUBSTANCES 577 



diosmose through the protoplasts and hence be transferred without under- 

 going any marked change, while oil may be absorbed or translocated in the 

 form of a fine emulsion. All the typical reserve-materials may be 

 transitorily deposited in the translocatory channels, and the appearance 

 of such storage substance in the latter seems to bear some indirect 

 relation to the activity of translocation. Glucose and starch are the most 

 commonly occurring non-nitrogenous products, while in many cases cane- 

 sugar appears and may along with other polysaccharides take a more 

 prominent part in translocation than is superficially apparent. Mannite 

 seems to serve as translocatory material in the Olive, glycogen in Fungi. 

 Fatty oils commonly subserve the same purpose, and according to Kraus l 

 this is also the case with malic acid in the Crassulaceae. Nitrogen is usually 

 translocated in the form of asparagin or other amides and of various 

 proteids, while in Pangium edide hydrocyanic acid acquires a similar 

 -importance. The ash constituents are frequently stored up in the form 

 of organic compounds and may undergo direct translocation as such, but 

 usually decomposition precedes mobilization, so that a portion of the phos- 

 phorus, sulphur, &c. travels in the form of inorganic compounds. The ash 

 constituents are usually absorbed from the soil as inorganic salts and are 

 transferred in this condition to all parts before they enter into metabolism. 



The aplastic metabolic products as well as the non-essential ash con- 

 stituents undergo similar translocation. Thus resins are transferred to 

 certain regions by means of cells or special canals, while carbon dioxide 

 often travels a long distance before it can be excreted. Hence when calcium 

 oxalate (Sect. 86) or tannins (Sect. 87) undergo translocation, it does not 

 follow that they are used in metabolism as nutritive material. The 

 mobilized products frequently do not accumulate to any extent; and in 

 certain cases no soluble carbohydrates can be detected during the active 

 translocation of starch. The small amount of these readily diosmosing 

 compounds present at any one time is of considerable importance, for in 

 this way not only is the danger of loss very much minimized but also any 

 concentration is avoided which might be injurious to the tissues. Not only 

 does no accumulation occur when consumption is active, but also when the 

 consuming cells have no power of passively secreting the food-materials 

 supplied to them. The latter is usually the reason why starch and sugar 

 are absent from the primary meristem of the root and stem, for no accumu- 

 lation occurs when the consumption is very much lessened by the stoppage 

 of growth due to imbedding in a plaster-of-paris cast. Soluble proteids 

 which give the biuret reaction with copper are commonly present in consider- 

 able amount in primary meristem cells, but disappear as the latter elongate. 

 An accumulation of starch, sugar, proteids, &c., as a preparation for subse- 



1 Stoffwechsel b. d. Crassnlaceae, 1886, p. 71. 

 Pp 



