174 Proceedings Columbia Biochemical Association [Sept. 



The Juice of the ripe fruit contains 1.57 per cent. of pentosans 

 and only traces of galacfan. After precipitation with lead acetate, 

 the Juice gave the anihne acetate reaction for pentose, but none for 

 galactose. The presence of fructose and gliicose in considerable 

 amounts was quite definitely estabhshed by several reactions char- 

 acteristic of these sugars. 



The dried mucilage of the prickly pear, when separated by pre- 

 cipitation with alcohol from a two per cent. Solution, contained 15 

 per cent. of galactan, 31 per cent. of pentosan and 12 per cent. of 

 ash. The mucilage in the aqueous extracts could not be separated 

 completely from cell fragments, starch, crystals of calcium Oxalate 

 and other solid particles that caused opalescence and turbidity. A 

 dilute Solution containing 1.5 per cent. of solid matter, rendered 

 fairly clear by repeated filtration through silk, had no effect on 

 polarized light. This was true of all the Solutions of mucilage ob- 

 tained in this work, both before and after subjecting them to acid 

 hydrolysis. Harley^^ reports having found a specific rotation of 

 + 38° for Opuntia mucilage, but places little confidence in his own 

 results, since the reading was made on a very dilute opalescent Solu- 

 tion and calculated from an observed rotation of + 6 minutes. 

 Hydrolysis of the mucilage by digestion for several hours with 1,25 

 per cent. sulfuric acid Solution produced a sugar that had properties 

 similar to arabinose. When its osazone was formed, oily globules 

 rose to the surface. The precipitate was darker than glucosazone, 

 readily soluble in hot water and melted at about 160° C. 



A 95 per cent. alcoholic extract of the dried stems, previously 

 treated with ether, contained a sugar with specific rotations made on 

 three separate Solutions of — 6.6°, — 8.25°, and — 7.1°. The 

 osazone produced from this sugar had properties similar to those of 

 glucosazone. These results indicate the presence of glucose and 

 fructose^ in this extract. 



A 60 per cent. alcoholic extract of the dried stems contained 

 a suhstance apparently intermediate in character hetween mucilage 

 and sugars. It did not reduce Fehling Solution before hydrolysis, 

 but was very readily hydrolyzed by dilute acid Solutions. Alcohol 

 stronger than 60 per cent. reprecipitated this material as a flocculent 



" Harley : Journal de Pharmacie, iii, pp. 6-193. 



