K.— BOTANY 203 



the properties of micro-organisms for bringing this about. The best 

 known of these methods is the Amylo process which was introduced 

 about forty years ago, and is utilised either in its original form, or in some 

 modification, in almost every country in the world where the fermentation 

 of starchy material is carried on. Several moulds have the power of 

 converting starch into sugar, but the species first patented by Calmette 

 and Boidin was Mucor (Amylomyces) Rouxii, 11 which Calmette had found 

 in ' Chinese rice,' used in various oriental fermentations. Sterilised 

 corn-mash in a closed vessel is inoculated with a very small quantity of 

 fungus and filtered air is blown through the fluid for several hours. The 

 mould develops very rapidly and converts the starch. Pure-yeast cultures 

 are added and develop in the ordinary way ; the species employed is 

 Saccharomyces anamensis from sugar-cane in Cochin China. Although 

 the Mucor itself is able to ferment the sugar, yeast acts more rapidly 

 and gives a greater percentage of alcohol. The process has been modified 

 with the years and other species have since been used in place of Mucor 

 Rouxii, first Amylomyces p (Rhizopus japonicus) and Amylomyces y 

 (R. tonkinensis) , and now Rhizopus Delemar. 12 A similar process is that 

 of Boulard in which Mucor Boulard No. 5 is employed, a species obtained 

 originally from grains in the Far East. This fungus is characterised by its 

 saccharifying power, and its ability to hold its own against infection ; 

 consequently the process is carried out in open vats much as in ordinary 

 grain distilleries. Mould and yeast are added at the same time, the 

 special yeasts employed being the rapidly acting Yeast Boulard Nos. 21-30. 

 Neither the Amylo nor the Boulard process has been adopted in countries 

 like England where the excise laws require that the gravity of distillers' 

 wort shall be determined before fermentation by the saccharimeter, 

 which is not possible where the two stages are simultaneous. Owing 

 to the adaptability of these processes to high temperatures they are 

 suitable for tropical and subtropical countries. 



Almost every nation has its ancient fermented drink. Kvass, the 

 commonest beverage in Russia, is usually prepared by mixing barley- 

 malt, rye-malt, and rye-flour in equal parts, stirring with boiling water, 

 allowing to stand for some hours, diluting with more boiling water, then 

 adding yeast. After incubating for two or three days peppermint is 

 added for flavouring. Kvass is served out as a ration to the Russian troops. 

 Similar beverages are prepared in Hungary, Yugoslavia and Roumania, 

 millet or maize being used and honey or sugar added. 



Pulque, the national beverage of Mexico, is prepared by fermenting 

 the juice obtained by tapping Agave, species of which are grown for the 

 purpose ; several millions of capital are sunk in the business. Some of 

 the juice is allowed to ferment naturally for about ten days and a small 

 amount of this is added to fresh juice. Fermentation proceeds rapidly, 

 and the drink is ready after a day or two. A couple of yeasts (No. 1 and 

 No. 2) have been recorded as responsible for the fermentation. Alcoholic 



11 The specific epithet is often wrongly written Rouxianus . The fungus has 

 also been isolated from soil from North Greenland. 



12 Several species of Rhizopus have been described from Japanese and Chinese 

 foods. 



