98 PLANT PHYSIOLOGY 



be those of the composition of the solutions. Make up the 

 following solutions and fill into the jars: 



1. Distilled water 



2. Complete culture solution (Sachs) 



3. Complete culture solution, omitting the KNO3 



4. Complete culture solution, omitting the ]\IgS04 



5. Complete culture solution, omitting the KXO3 and 



K2SO4 and adding Ca(N03)2 in place of the first. 



6. Complete culture solution, omitting theCa3(P04)2 



and adding an equal amount of Ca(N03)2 



7. Complete culture solution, omitting theK2S0i and 



MgS04 and replacing by an equal amount of 

 Mg(N03)2 



8. Complete culture solution omitting the Ca3(PO.i)2 



and substituting K2HPO4 



9. Complete culture solution omitting the FeCU. 

 The Sachs' solution consists of: 



Distilled water 1000 cc. 



KNO3 1 gm. 



K2SO. 0.5 gm. 



MgS04 0.4 gm. 



Ca3(PO02 0.5 gm. 



FeCls trace. 



Let the plants grow for several weeks, rej^lacing the old 

 solutions by fresh ones of the same composition every week or 

 so. Compare the amount of growth of both roots and stems in 

 the different solutions, the size and color of the leaves, etc. 

 Note when growth ceases and to what stage of development 

 the plant proceeds before its death. 



(c) Bring some Spirogyra into the laboratory and place 

 in a dark room (not too cold) for twentj'-four to thirt^^-six 

 hours or until on testing some of the plants with iodine solution 

 no starch is found. Bring the dish into the sunlight and with 

 iodine solution test some of the plants for starch after five 

 minutes, ten minutes, half an hour, etc. 



(d) In a rather broad, deep glass dish (e.g. a wide battery 

 jar) place some actively growing Spirogyra. Put a bit of wire 

 netting (iron, not copper nor brass) into the bottom of a short- 

 tubed funnel and invert over the Spirogyra submerging the 



