FIRST PART. 



Physiology of Nutrition. 



FIRST SECTION. 

 The Food of Plants. 



I. ASSIMILATION". 



1. Proof of the Fact that Green Plants are Able to Produce 

 Organic Substance from Inorganic Material. 



THE fact that green plants can produce organic, i.e. carbonaceous, 

 combustible substance from inorganic material, is of such funda- 

 mental significance, and the experiments to be made in order to 

 establish it are so instructive, that very special attention must 

 be paid to it. The investigations can be made at almost any 

 time of the year; they certainly give by far the best results in 

 summer owing to the favourable conditions for vegetation then 

 prevailing, and if we are intending experiments in which the 

 plants are to be brought to full development and seed ripening, 

 it is clear that winter will not answer our purpose. For re- 

 search material we may employ maize, wheat, oats, buckwheat, 

 or beans. 



It is first necessary to ascertain the dry weight of the dormant 

 fruits or seeds used, in order to determine the quantity of organic 

 substance contained in them. A few fruits or seeds are ground to 

 a fine powder in a small hand-mill, and a small quantity of this 

 powder, whose weight however must be accurately ascertained, 

 will serve for the determination of the amount of dry substance 

 contained in the originally air-dry material. About 3 gr. of the 

 powder is placed in a suitable glass (weighing glass), and freed 

 from water at 100 C. in the drying chamber. It is found that 

 the air- dry fruits or seeds contain about 85 per cent, of dry sub- 



P. P. B 



