THE FORMATION OF PROTEIDS IN PLANT-CELLS. 65 



To effect the synthesis of proteids, — especially in the 

 last phases — a certain amount of energy is required. This 

 energy is procured by respiration. Respiration, however, also 

 brings on the partial oxidations necessary for transforming 

 glucose into asparagin or aspartic aldehyde. Where respira- 

 tion is impeded, the protein production will be retarded. It 

 is, therefore, not surprising that in the interior of potatoes 

 and beets, asparagin is found in company with starch and 

 reducing sugar and that the stem of plants contains more as- 

 paragin than the leaves, as Schulze has found. The stalks 

 of Medicago sativa contain 7 times as much asparagin as the 

 leaves. Stems and cotyledons of young lupin-plants cultivated 

 first in the dark and afterwards 4 weeks in daylight, contained 

 18,4% asparagin, the young leaves, however, only 6%. The 

 structure of the leaves and their numerous stomata certainly 

 secure a much more energetic respiration than the structure 

 of stems, roots and bulbs. As respiration is best supported by 

 carbohydrates, it is clear that glucose plays a still more im- 

 portant role in protein formation : it yields chemical energy, and 

 as the leaves produce by assimilation of carbonic acid a large 

 amount of glucose, it follows that the leaves must be the most 

 favorable organs of the plants for the production of proteids. 

 The sun-rays are thus indirectly a great supporter of protein- 

 formation. Directly, however, no such influence is required, 

 as I have shown in experimenting with mould-fungi grown in 

 the dark and in diffused day-light ; not only was the develop- 

 ment of the fungus just as energetic in the dark as in the 

 light but in some cases it even exceeded the latter. Here 

 glucose and glycerin served as organic nutrients. 1 ) 



But while access of air is indispensable for the production 

 of asparagin and proteids, such is not the case for the action 

 of the enzymes in peptonising and decomposing the reserve 

 proteids in the germinating seeds. Palladin has proved that 

 shoots, — which remain alive in the absence of air for 24 hours — 

 cease to produce asparagin under this condition, 2) while the 

 production of amido-acids by enzyme is still going on. 



Glucose is in more than one respect highly important for 



1) O. Loew, Biol. Centralbl. 10, 584. 



2) Ber. d. Deutsch. Botan. Ges. 6, 205 and 269. 



