VEGETABLE CYTOLOGY 85 



either corm or seed be treated with a mixture of i part of H 2 SO 4 

 and 3 parts of H 2 O, the cells containing colchicine will be colored 

 yellow. If a crystal of KNO 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 (C28H 47 NOii) which is found 

 in Solanum 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 i 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 O). 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 Alth&a 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. 



