7o8 CHEMICAL PROCESSES IN THE PLANT. 



by oily matter ; and it cannot be doubted that this furnishes the material for the 

 growth of the cell-walls when the new organs are being formed. 



To the series of these substances of the same physiological value belongs 

 finally cellulose itself, which may also be deposited in considerable quantities as a 

 reserve-material, as in the endosperm of the Date, the greater part of the hard kernel 

 of which consists of cellulose in the form of the pitted thickening masses of the 

 cell-walls. These are dissolved during germination, and the products of their solu- 

 tion conveyed to the growing parts of the embryo, where they finally supply the 

 material for the growth of the new cell-walls. 



If on the other hand the substances which occur in dormant seeds, bulbs, 

 tubers, and other reservoirs of reserve-material, are compared with those which are 

 found in the conducting tissues and growing organs of seedlings and young roots — 

 which we already know must necessarily be produced from the former, because there 

 is no other material which can produce them — it is seen that these reserve-materials 

 must undergo repeated Metamorphosis while they are being conveyed to the growing 

 organs and are being consumed in the process of growth, and before the permanent 

 form of cellulose has been attained.* Thus sugar and starch are found temporarily 

 in all oily seeds during germination, and are often accumulated in great quantities, 

 disappearing when germination is completed. In proportion as they are formed the 

 amount of the original oil decreases ; and in proportion as they again disappear the 

 quantity of cellulose in the cell-walls increases. In other cases starch is conveyed 

 from reservoirs of reserve-material to the growing organs, sugar being at the same 

 time formed^; and fine-grained starch is again temporarily formed in the growing 

 tissues themselves, disappearing once more with the growth of the cell-walls. This 

 temporary formation of starch in the growing . tissues themselves is an extremely 

 common phenomenon, whether the reservoirs of reserve-material were filled with 

 oily matter, inulin, sugar, starch, or cellulose. This transitory starch appears in the 

 cells of the parenchyma and epidermis of young organs (only rarely in those of the 

 fibro-vascular bundles) after they have become differentiated from the primary meri- 

 stem ; and disappears when the final elongation of the organs is completed, generally 

 becoming transformed into sugar (glucose), which in its turn speedily disappears. 



Transitory metamorphoses also take place when the albuminoids stored up in 

 the reservoirs of reserve-materials are being transported and consumed^; although 

 these metamorphoses cannot be followed by micro-chemical observations, as in the 



^ [The conversion of starch into sugar is effected by means of unorganised ferments ; some of 

 these have long been knovi^n, such as Emulsin (in Almonds), Diastase (in Barley), Myrosin (in Black 

 Mustard seeds). More recently they have been detected in various plants and parts of plants by 

 Kossmann (Journ. Pharm. Chem. (4) 22) and by Krauch (Landwirthsch. Versuchsstat, 23). Von 

 Gorup-Besanez has found ferments of this kind in the germinating seeds of Vetches, Hemp and Flax, 

 which have also a peptic action (see infrd)?^ 



^ [The first stage in the metamorphosis of the reserve-proteids is, doubtless, their conversion 

 into peptones, into proteid substances, that is, which are readily soluble in water and which diffuse 

 rapidly. This is effected by the action of unorganised ferments. These bodies have been found in 

 germinating seeds (v. Gorup-Besanez and Will) and in the secretion of ' carnivorous ' plants such as 

 Nepenthes, Drosera, and Darlingtonia. Recently a very active peptic ferment has been found in the 

 green fruits of Carica Papaya (Wiirtz and Bouchet, Le Papain, Comptes rendus, torn. 89, 90, and 91).' 



A good resume of our knowledge on the action and distribution of unorganised ferments in plants 

 is given in the second edition (1882) of Husemann's Pflanzenstoffe, I. p. 537.] 



