52 CELL-CONTENTS AND CELL-WALLS. 



Cut sections of the various parts of the seedling, at different 

 stages, and note that the protein diminishes in amount during 

 germination as the formation of asparagin increases. Eventually, 

 asparagin practically disappears from all the organs. 



(e) Germinate some Lupin seeds in darkness, and compare them 

 with those grown in light as regards their asparagin and protein 

 contents. Note that after a few weeks the seedlings grown in 

 darkness contain asparagin, while those grown in the light contain 

 little or none. 



(/) Get two similar Lupin seedlings, germinated in darkness in 

 a water culture jar, with a well developed root-system. Place one 

 (^4) on a wooden board or glass plate, along with a bottle containing 

 baryta-water, or a dish of soda-lime ; cover with a tubulated bell- 

 jar, sealing the edges of the jar to the plate with wax mixture, 

 putty, or plasticine. Fit the mouth of the jar with a cork, bored with 

 three holes. Through one hole pass a tube through which water 

 can be poured to replenish that lost by the culture solution owing 

 to evaporation ; for this purpose join the upper end of the tube by 

 rubber tubing to a funnel, placing a clip on the rubber tubing. 

 Through the other two holes pass pieces of glass tubing, one joined 

 up to a bottle containing baryta-water, the other to an aspirator. 

 The general arrangement of the apparatus is somewhat similar to 

 that shown in Fig. 44. The object is to grow the seedling in air 

 deprived of carbon dioxide, but to give it daily aeration by drawing 

 through the bell-jar a current of fresh air (deprived of carbon 

 dioxide by passing through the vessel of baryta- water). For com- 

 parison, place the second seedling (B) on a similar plate and cover 

 with a bell-jar, but leave the neck of the jar open, so that the seed- 

 ling is supplied with the ordinary air. After a few weeks, note 

 that A still contains large amounts of asparagin, though this will 

 have practically disappeared from B. 



V. STARCH, SUGARS, DEXTRIN, INULIN. 



61. Carbohydrates contain Carbon, Hydrogen, and 

 Oxygen, with the hydrogen and oxygen in the same pro- 

 portion as in water (two atoms of hydrogen to each atom 

 of oxygen). Formaldehyde (CH 2 O) has the empirical 

 formula of a carbohydrate, and is in fact the first member 

 of the series, which includes members with 2, 3, 4, 5, 6, etc., 

 carbon atoms. The chief carbohydrates those of physio- 

 logical importance are the members with six carbon 

 atoms, or some multiple of six. The simple six- carbon- 

 atom compounds, or hexoses, e.g. glucose, belong to the 



