CH. XVIl] EXPERIMENTS. 313 



and cellulose in B will be the amounts formed per day by 

 the weight of Spirogyra taken. 



(2) Shew that formation of starch is influenced by 

 supply of inorganic salts. 



Take some young leaves of Sparganium naUvns (or 

 shoots of Elodea canadensis) and grow one portion {A) 

 in pure distilled water, and another portion {B) in a 

 culture solution, both being freely exposed to light and 

 air, for several days. 



Determine in portions of A the p.c. of starch (if any) 

 and the p.c. of (sulphated) ash. 



Do. in portions of B. 



(3) Trace the changes which occur during germina- 

 tion in the reserve materials of an oily seed under 

 different conditions. 



Take three equal weights (about 10 grs. each) of air- 

 dried hemp-seeds {A), (B), (C). 



Allow B and C to germinate on damp asbestos cloth and 

 when the plumules have reached a length of 2 — 3 cm., 

 place B in a bell-jar arranged so as to exclude CO 2^ : place 

 C under similar conditions, but with free access to COo : 

 leave B and C exposed as much as possible to light for 

 about a fortnight. Then kill them by chloroform vapour 

 and dry at 25°— 30°. 



Note weights (air-dried) of ^ , B, and C. 



Make extracts of aliquot portions of A, B, and G, and 

 determine for each of them, (1) nitrogenous compounds, 

 (2) oils and fats, (3) sugars, (4) starch, (5) cellulose. 



1 See Part I., Fig. 8, p. 30. 



