84 



thick syrup would not ferment, but would do so 

 if diluted. Evaporation would, however, be an 

 expensive matter. 



The conclusions of these authors may be 

 stated briefly. In order to make alcohol manu- 

 facture from prickly-pear fruit a profitable under- 

 taking, the following conditions would seem to be 

 necessary: — (1) The production of a large 

 amount of fruit from small areas averaging about 

 10 tons of fruit to the acre; (2) Some rapid 

 method of collecting fruit, as hand-picking even 

 with Mexican labour is too expensive.* 



It should be mentioned, however, that these 

 findings have reference to the manufacture of 

 raw spirit, and not to an immediately potable 

 beverage which, as already known, prickly-pear 

 fruits may be made to yield. 



UTILISATION OF THE MUCILAGE OF 

 PRICKLY-PEAR. 



Dr. Hare (1911), in his "Preliminary Study 

 of the Carbohydrates in the Prickly Pear and its 

 Fruits, ' ' deals with the mucilage contained in the 

 stem-joints as well as in the green fruits. This 

 substance disappears from the latter as ripening 

 progresses, and is absent from mature fruits, 

 being replaced by sugars, largely "glucose and 

 fructose with small amounts of sucrose and per- 

 haps a pentose in smaU amounts, but no galac- 

 tose." His analysis of the mucilage from the 

 stem showed that it contained galactanf and a 

 pentosan. The carbohydrates of the stem were 

 found to consist mainly of this mucilage together 

 with small quantities of gum, sugar, and starch, 

 the latter being present during summer, but scarce 

 or absent at other times of the year. Dr. Hare 

 thought that 'Sullivan's view that mucilages 

 and gums are not polysaccharides as usually 

 believed, but are glucoside derivatives of certain 

 organic acids — the latter being different for each 

 mucilage — was the correct one in the case of 

 Opuntia. 



The prickly-pear mucilage was observed to 

 be insoluble in water, as its "solution" in water 

 wiU not pass through unglazed porcelain, though 

 if dilute it will pass through filter paper. It was 

 also found that this substance could be separated 

 by certain treatment with alcohol into two con- 

 stituents, one of which contained a high percen- 

 tage of pentosans while the other was free from 

 them, but was easily hydrolised to produce 

 hexoses. The composition of the dried mucilage 

 "when separated by precipitation with alcohol 

 from a 2 per cent, solution contained 15 per cent, 

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

 cent, of ash," whereas the juice of the ripe fruit 

 contained 1.57 per cent, of pentosans, and only 

 traces of galactan, but considerable quantities of 

 fructose and glucose (p. 28). 



In regard to the question of utilising the 

 mucilage, Prof. Hare found that though a 10 per 

 cent, solution was very viscous, its adhesiveness 

 was very poor. He mentioned that experiments 



* Mexican labour is obtained at an extremely cheap 

 rate ia Mexico and the neighbouring parts of the United 

 States, when compared with the cost in such a country as 

 Australia {see Griffiths, 1905, pp. 42-43). 



t K. Yoshimura, in his " Note on the Chemical Com- 

 position of some Mucilages," in the Bull. Coll. Agricul Imp. 

 University, Tokyo, Japan, (2, 1895, pp. 207-8), found that 

 the mucilage from the stem of prickly-pears consisted 

 chiefly of galactan, whereas Ladd (New York Agric. Exp. 

 Station, 6th Ann. Rep. ) thought it contained pectins his 

 conclusions being doubted by Griffiths and Hare (1967 b 

 p. 40). .^ . ., 



carried out by a manufacturing firm to test the 

 usefulness of prickly-pear mucilage as a glaze for 

 paper showed that it was unsatisfactory on 

 account of the feebleness of its adhesive qualities. 

 Mr. Luther Burbank informed the Commission 

 that he believed that the substance had been used 

 to some little extent in the United States of 

 America as a glaze for cheap cotton stuffs. 



The mucilage obtained from 0. engelmanni 

 in Southern California is used as a dressing for 

 canvas tents employed in fumigating fruit-trees. 

 Joints are chopped up and then soaked in water 

 for twenty-four hours, the mucilage obtained 

 being thickened by the addition of ochre or Vene- 

 tian red and then applied to both sides of the 

 canvas.* 



The industrial arts may, however, furnish 

 other opportunities for the use of prickly-pear 

 mucilage, an instance of this being given in the 

 section of the Report dealing with India, where 

 the substance is utilised in the making of a kind 

 of plaster (chunar). 



THE COLOURING MATTER OF PRICKLY- 

 PEAR FRUIT. 

 The fruits of many prickly-pears contain a 

 bright' magenta colouring, which in the case of 

 0. dulcis has been investigated by Dr. Hare 

 (1911). t He first removed the mucilaginous 

 material from the juice by the addition of one 

 or two volumes of alcohol. The addition of two 

 volumes of acetone to the filtrate precipitates the 

 magenta pigment in a syrupy condition. The 

 latter can be dried and its colour is permanent. 



Experiments were made with wool, silk, and 

 cotton, mordanted and not mordanted, but it was 

 found that the colour did not form a sufficiently 

 fast dye. As an article for colouring foods and 

 drugs, it Avas proved unsatisfactory in cases where 

 it was necessary to keep the colour in solution in 

 the presence of oxidising agents or light, but was 

 found to give quite satisfactory results when used 

 to colour ice-cream, beverages, candies, and fruit 

 preserves. 



He believed that on account of the cheapness 

 and abundance of the fruit, and the ease with 

 which the pigment could be separated and concen- 

 trated into a harmless paste suitable for use in 

 colouring certain foodstuffs, its introduction to 

 the trade would be justified. 



SUMMARY OF INVESTIGATIONS IN THE 

 UNITED STATES. 



The Commission visited the main cactus 

 areas and obtained advice and assistance from 

 various scientific workers and others who had 

 given attention to prickly-pear matters. 



In regard to destruction by disease, there is 

 one malady, anthracnose or " shothole," caused 

 by the fungus Oloeosporium lunatum, which, 

 under certain conditions of climate, is capable of 

 causing considerable damage, the " black rot" 

 which then sets in bringing about the destruction 

 of attacked segments. Cultures of this fungus 

 have been brought to Queensland by the Com- 

 mission. * 



* Year book of Agriculture, U.S.A., 1896, p. 230. 



t A short preliminary account was published by 

 Griffiths and Hare (1907 b, p. 62), th^ gpecies being 

 identified as O. ?»w ?, Coulter. ' 



