Vol. IX. No. 215. 



THE AGRICULTURAL NEWS. 



235 



similar to the cold weather of temperate regions. Under 

 normal conditions, the female tick undergoes all its devel- 

 opment, from the attachment of the seed tick to the 

 dropping oti' of the fully fed adult, without leaving the host 

 animal. That is to say, any given tick only feeds on one host 

 animal. From this it will be seen that the fever is not 

 transmitted by the tick which was fed on an infected animal, 

 but by the seed ticks which hatched from the eggs laid by 

 an infected adult. 



THE 



UTILIZATION OF 

 PEAR. 



THE PRICKLY 



The following discussion as to the feasibiiit}- of 

 using the prickly pear in various ways is taken from 

 an article in the Bulletin <if IIk' I iiijieTial Institute, 

 Vol. VIII (1910), p. 43. It will be seen to contain 

 much information that is of a useful nature: — 



In 1908, the remarkable announcement was widely 

 published that a chemist in Bri.sbane had discovered valuable 

 commercial possibilities for the prickly pear, which led him 

 to conclude that, in.-itead of the plant being ruthlessly 

 destroyed, its cultivation ought to be encouraged. The 

 principal claims put forward were (1) that from 1 ton of 

 prickly pear 7 gallons of alcohol could be prepared at a c>st 

 not exceeding is. 6iZ. per gallon, whilst the refuse could be 

 made into a nutritious cattle-food; (J) that the plant yields 

 an excellent sugar, 2 tons of prickly pear yielding as much 

 sugar as 3 tons of .sugar-cane, and of equal quality; and (3) 

 that the fibrous nature of the material renders it suitable for 

 the manufacture of paper, straw-ooard and other articles, and 

 that these could be more cheaply produced from prickly pear 

 than from any product now used for the pur|)ose. 



The suggestion with regard to utilizing the plant for the 

 manufacture of alcohol is not new. I'rojiosals of this kind 

 have been made previously in Xew South Wales, Mexico, 

 Spain, India, and other countries, but it docs not appear that 

 alcohol has ever been obtained from this source on 

 a commercial scale. The juice ol' the fruit contains saccharine 

 matter, and untlergoes spontaneous ferment^ition; the 

 alcoholic liquid thus obtained is used by the natives of 

 Mexico and other countries as a beverage. It seems improb- 

 able, however, that this liquid could be i)rofitably eni[)loyed 

 as a source of alcohol, for the following reasons. 



Alcohol of 90 per cent, strength can be manufactured 

 from cheap materials, such as maize and potatos, at a cost 

 of from 6<7. to \s. per gallon, depending on the market price 

 of the raw materials, and other local factors. It is evident, 

 therefore, that the production of spirit from prickly pear juice 

 could only be remunerative in a country which had no other 

 crops available for the purpose, and which had a heavy duty 

 on imported alcohol. Moreover, the researches of Ulpiani 

 and fearcoli, in 1902, have shown that not only would the 

 manufacture of alcohol from prickly pear juice be unprofit- 

 able, but also that it is scarcely practicable. These chem- 

 ists found that the juice of the fruit of the prickly pear con- 

 tains 128 per cent, of sugar, which consists not of sucro.se 

 (or cane-sugar) but of a mi.xture of glucose and fructose. The 

 spontaneous fermentation of the juice is due to the action of 

 a natural yeast which occurs on the fruit, and has been term- 

 ed Saccharomycts opuntiae. This yeast does not ferment 

 cane-sugar, but only glucose and fructose. The fermenta- 

 tion takes place very slowly, and even after a long time the 

 proportion of alcohol is not equivalent to the amount of 

 sugars originally present. Added yeast, however, is 



rapidly suppressed by S. opuntiae, and it would there- 

 fore be necessary to kill the latter by sterilizing the juice 

 before introducing the ordinary yeast. On account of the 

 expense of sterilization, it is regarded as desirable to find 

 a yeast capable of producing alcohol rapidly in the presence 

 of the neutral yeast (>S'. opuntiae), as only in this way could 

 the manufacture of alcohol from the juice become practicable. 



With regard to the manufacture of sugar from the prick- 

 ly pear, it is obvious that if the contention of Ulpiani and 

 Sarcoli, that the juice contains only glucose and fructose is 

 correct, no cane-sugar could possibly be obtainable. 



With reference to the utilization of the prickly pear for 

 paper-making, experiments at the Imperial Institute have 

 shown that a pulp can be prepared by the process of heating 

 the fibre of the plant with caustic alkali under pressure, but 

 that the product so obtained consists of very short fibres 

 (about •125--33 inch long), and would therefore be of ctmipara- 

 tively low vauie. Samples of the fibre of a South American 

 species (Opuntia Dillenii), which occurs in India, were shown 

 at the Colonial and Indian Exhibition which was held in Lon- 

 don in 1886. Paper makers who examined these samples, how- 

 ever, regarded them as worthless in comparison with 

 other cheap and plentiful materials. It is probable 

 that the collection of the raw material would be 

 a costly operation. Moreover, a little consideration will 

 show that an immense quantity of the plant would have 

 to be dealt with in order to produce a comparatively small 

 amount of paper pulp, .\nalyses of various parts of the 

 prickly pear at ditterent ages in the United States of America 

 (liureau of Plant Industrt/, liulletin Xo. 101, Part 1, United 

 States Dejiartment i>/ A(/rindtnre, 1907) have shown that, on 

 the average, the fresh plant contains S-l'S per cent, of water 

 and 24 percent, of 'crude fibre'. Experiments at the Imperial 

 Institute have proved that 100 parts of dry prickly pear fibre 

 yield about 42 parts of dry paperpulp. Hence from 2'4 parts 

 of the crude fibre about 1 part of the pulp could be obtained. 

 It is true that the 'crude fibre' of the analysis was extracted 

 by a dirterent process from that used in the preparation of 

 the fibre employed in the Imperial Institute experiments, but 

 this would not greatly afl'ect the results arrived at. It is 

 evident, therefore, that for the manufacture of 1 ton of 

 paper pulp it would be necessary to cut about 100 tons of 

 the fresh plant. When to the cost of collecting and handling 

 this mass of material is added that of the chemicals and 

 labour required for the extraction of the fibre and its con- 

 version into i)aper pulp, it seems evident that the project could 

 not possibly be remunerative, especially as the product is of 

 low qualit}', and would not in any case be worth more than 

 a few pounds per ton. 



In conclusion, it appears that the only purpose for which 

 the prickly pear could be used .successfully is as a cattle food. 

 Opinions with regard to the value of the material for this 

 purpose are, however, very conflicting, and, at best, it would 

 constitute a product of somewhat low nutritive value, and 

 could only be used in conjunction with richer feeding stuffs, 

 such as wheat bran or cotton seed meal. In the previous 

 article on this subject {Bulletin, 1908, 6, 314) allusion was 

 made to the production of a spineless variety of prickly pear 

 in California. It does not appear safe, however, to encourage 

 the cultivation of such forms until they have been subjected 

 to prolonged trials, especially as there is always a danger that 

 they may revert to the spiny condition. Trials have been 

 made recently in South Africa with so-called spineless varieties, 

 which have proved to be not altogether spineless, but are, 

 nevertheless, regarded as much superior to the ordinary spiny 

 forms as a feeding-stuif for cattle. 



