98 PLANT PHYSIOLOGY 
be those of the composition of the solutions. Make up the 
following solutions and fill into the jars: 
Distilled water 
. Complete culture solution (Sachs) 
. Complete culture solution, omitting the KNOs 
. Complete culture solution, omitting the MgSO. 
. Complete culture solution, omitting the KNO; and 
K.SO, and adding Ca(NOz): in place of the first. 
6. Complete culture solution, omitting the Cas(PO.)2 
and adding an equal amount of Ca(NOs)e 
7. Complete culture solution, omitting the K2SO, and 
MgSO, and replacing by an equal amount of 
Mg(NOs3)2 
8. Complete culture solution omitting the Cas(POu.)2 
and substituting K,HPO, 
9. Complete culture solution omitting the FeCls. 
The Sachs’ solution consists of: 
oR ON ee 
Distilled water............... 1000 ce 
KN Os; SS Rae Se en oe one e Rae 1 gm 
K.S0O.4 PAE fr WE ah oe he NaC ee, ee 0:3 gm. 
MgSO, Sr ee ee ee 0.4 gm. 
CORPO Oa. es oe a eee 0.5 gm 
PA ee es ee ee trace 
Let the plants grow for several weeks, replacing 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, ete. 
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 twenty-four to thirty-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. Puta bit of wire 
netting (iron, not copper nor brass) into the bottom of a short- 
tubed funnel and invert over the Spirogyra submerging the 
