METABOLIC PROCESSES IN THE PLANT. 251 



ordinary proteid. Nevertheless, apart from this and a fe\v other 

 observations, the method referred to, although in principle nothing 

 can be urged against it, has led to no very valuable results. Thus, 

 e.g., from a strict chemical standpoint, we cannot consider most 

 of the results obtained in this direction by Frank Schwartz (see 

 Colm's Beitrilge zur Biologie d. Pflanzen, Bd. 5, H. 1) to be of any 

 value. 



1 See Sachs, Pringslieim's Jahrliicher, Bd. 3, p. 187. 

 - See Pfeffer, Pringsheim's Jahrbiicher, Bd. 8, p. 538. 



5. General Considerations Respecting the Behaviour of Proteids 



in Plants. 



The aleurone grains of seeds have already been mentioned in 

 another place. They contain large reserves of proteid, and just 

 as starch grains undergo important changes in the germination 

 of seeds, so also do the aleurone grains undergo changes when 

 germination begins. ' The protein grains, viz., are dissolved, and 

 their substance is utilised for the formation of living protoplasmic 

 structures. To convince ourselves that such solution does take 

 place, we need only germinate seeds of Ricinus commuiiis, and 

 then examine as thin sections as possible of the endosperm. The 

 proteid grains are no longer seen as glistening structures, as in 

 dormant seeds ; their outer part is dissolved up, and mixed with 

 the ground substance to form a cloudy emulsion. 



If we grind up lupin seeds in a hand mill, and treat the powder 

 with water, we can readily determine that large' quantities of 

 proteid are present in the solution. We need only heat the fluid 

 to boiling, and add some potash and a drop of Fehling's solution. 

 On treating lapin seed powder with water, and also on soaking 

 uninjured seeds, it is conglutin which especially passes into solu- 

 tion. But this proteid is insoluble in pure water. Therefore 

 substances must be present which assist its solution. If we test 

 the reaction of the lupin powder extract by means of litmus 

 paper, it is found to be somewhat strongly acid. This acid re- 

 action is in some cases due to the Citric acid which is present in 

 many kinds of lupin (and conglutin is of course soluble in Citric 

 ncid) ; it may, however, be due to another cause. If we stir up 

 some conglutin in water, the fluid becomes at most only very 

 slightly acid in reaction; but if we now add a solution of Potas- 

 sium phosphate (K 2 H P 4 ), which itself has a slight alkaline 



