VEGETABLE CYTOLOGY 
85 
either corm or seed be treated with a mixture of 1 part of H 2 S 0 4 
and 3 parts of H 2 0 , the cells containing colchicine will be colored 
yellow. If a crystal of KN 0 3 then be added the color will change 
to a brownish-violet. 
10. Gluco-alkaloids. —These are compounds intermediate in 
nature between alkaloids and glucosides, having characteristics of 
each. To this group belongs solanine (C 28 H 47 NOn) which is found 
in Solarium nigrum, Solanum Dulcamara, Solanum carolinense and 
other species of the Solanacea. When sections of those plant parts 
which contain this constituent are mounted in a solution of 1 part 
of ammonium vanadate in 1000 parts of a mixture of 49 parts of 
sulphuric acid with 18 parts of water, the cells containing solanin 
take on a yellow color which changes successively to orange, various 
shades of red, blue-violet, grayish-blue and then disappears. 
14. Asparagine (C 4 H 8 N 2 + H 2 0 ).—This is an amino compound of 
crystalline nature which occurs widely in the plant kingdom. It 
has been found in certain of the slime molds and fungi, in the roots 
of Althaea officinalis and Atropa belladonna, in young shoots of 
Asparagus, in the seeds of Castanea dentata, in the tubers of Solanum 
tuberosum and varieties of Dahlia, and is known to play an important 
part in metabolism. Stevens claims that proteids are reduced for 
the most part to asparagine during seed germination. 1 If thick sec¬ 
tions are cut from a plant part containing this substance and 
mounted in alcohol, rhombohedral crystals of asparagin in the form 
of plates will be deposited upon the evaporation of the alcohol. If 
to these a few drops of a saturated solution of asparagine are added 
the crystals already formed will increase in size. To get satisfactory 
results the saturated solution must be of the same temperature as 
the mount. 
15. Calcium Oxalate. —This substance occurs in many plants 
always in the form of crystals. It is apparently formed by the reac¬ 
tion of salts of calcium, which have found their way into the cell 
sap from the soil, with oxalic acid which is manufactured by the 
plant. Calcium oxalate crystals dissolve readily in mineral acids 
without effervescence. They are insoluble in acetic acid or water. 
1 Stevens’ Plant Anatomy, 3d Edit., p. 189. 
