CHAPTER XVII. 



GENERAL EXPERIMENTS. 



G-eneral Experiments. 



(1) Determine the increase per day of nitrogenous 

 compounds and cellulose in vigorously growing Spirogyra. 



Take some healthy Spirogyra which has been well 

 washed in distilled water, filter and allow it to drain on a 

 perforated filter plate. Weigh out two equal portions 

 (about 15 — 20 grs. each). Place one portion (B) in 

 ordinary water and expose it to bright sunlight. Dry the 

 other portion (A) at 30°, and note its dry weight. 



Extract one portion of A with 2 p.c. soda and deter- 

 mine the proteids in the extract (nitrogen by Wanklyn's 

 albuminoid ammonia process, v. p.. 237). 



Extract another portion of (A) with dilute alcohol and 

 then with 1 p.c. sulphuric acid and treat the residue 

 with ammonia and bromine water (v. p. 275) : then dry 

 the residue at 100° and weigh ( = cellulose). 



At the end of twenty-four hours take out the whole of 

 B and wash thoroughly with distilled water ; then collect, 

 dry, and treat in same way as A. The increase of proteids 



