474 The American Naturalist. [May, 
A normal “culture solution’ was prepared with the following 
composition : 
Potassium nitrate(KNO,).....- - 0.15 grams. 
Magnesium chloride (MgCl,). . - . . Gio 
Calcium phosphate (Ca,(PO,),). - . .9.05 “ 
Ferrous sulphate (FeSO,). ....- 0.025 ‘ 
Calcium sulphate (CaSO,). - ...- - aso o 7 
Water (Gites) u o a aoa A 100. n 
This was placed in the culture cylinder, and to this were added the 
organic compounds experimented with. The plants used were either 
cut branches, or plants with roots, and these were supported by a cork 
in the mouth of the culture cylinder, in the usual way. Application 
of the organic compound were also made directly to the surfaces of 
the leaves of plants. 
The plants used were first deprived of all their starch, either (a) by 
being placed in the dark for a sufficient length of time, or (b) by 
being placed under the bell-jar described above, where, having no 
access to carbon dioxide, the same result was obtained with greater con- 
venience. After such preparation they were placed in the culture solu- 
tion, to which an organic compound had been added. On exposure 
to light in some cases starch was formed, although all access of carbon 
dioxide was cut off,thus proving that the plants formed starch by con- 
version of the organic compounds. The results were as follows : 
1. Neither acrolein nor acrolein ammonia (C,H,NO) were used by 
the plants. No starch whatever was form 
2. With allyl alcohol (C,H,O) similar soit were obtained. 
3- With glucose (one per cent. solution) starch was produced in 
every instance. 
4. With aldehyde no starch was formed. 
5. With weak solution (0.05 to ro per cent.) of pure glycerine 
starch was invariably formed. 
6. With levulinic acid no starch was formed. 
7. With pure cane sugar starch was invariably formed. 
8. With dextrine no starch was formed. 
g. With inulin starch was formed. 
to. With ‘soluble starch’’! the cut branches formed starch, but 
those supplied with roots did not. 
11. With glycogen no starch was formed. 
1Soluble starch was by rubbing 
ee piney pouring it into 0an ee of boi kelisa ube gaa C aa 
ing, gh paper, and diluted toa strength of about 

