K.— BOTANY 213 



adding a disinfectant ; for food or medicinal use it is concentrated or 

 precipitated by alcohol. The product is not pure diastase, but a mixture 

 of enzymes — it has even been called an arsenal of enzymes — hence the 

 commercial name Polyzyme. 



Takadiastase, a whitish or yellowish powder, is used in medicine where 

 there is a lack of normal digestive activity, especially that of ptyalin. 

 Owing to J. Takamine working in America — he went there in 1891 with 

 the idea, he says, of introducing the use of Aspergillus Oryzce, which plays 

 such an important part in the natural economy of Japan — and taking out 

 his first patent in 1894, his diastase has been largely employed there in 

 industry. In the weaving of fabrics from cotton, jute and similar fibres, 

 it is often necessary to oversize the warp threads to facilitate weaving. 

 This extra size is removed by an enzymic solution. Takadiastase is also 

 employed to separate the silk fibres comprising the thread as spun by 

 the silkworm. It is also used for clarifying the pectin of apple pomace 

 in jam and jelly-making — the turbidity is due to starch and protein — 

 and to clear sorghum syrup. Commercial diastase can replace soap in 

 laundry work and is a partial substitute for yeast in bread-making. 



Investigations carried out during the last forty years on the growth 

 of moulds in culture show the possibilities of the utilisation of their 

 action on sugars and other carbohydrates. The work of Pasteur and his 

 pupils was followed up in many countries, but progress was slow. 



In 1 89 1 C. Wehmer began a series of researches which altered the whole 

 complexion of the subject. He was the first to recognise oxalic acid as 

 a definite fermentation product of many fungi— Aspergillus , Penicillium, 

 Mucor. By adding calcium carbonate to a medium consisting of sugar 

 and inorganic salts he showed that Aspergillus niger would give yields 

 of calcium oxalate up to 120 per cent, of the sugar. The investigation 

 led to no commercial result as oxalic acid can be produced more 

 economically by purely chemical methods. 



Wehmer in 1892 showed that citric acid was a product of fermentation. 

 He obtained excellent yields in cultures where sugar was the only source 

 of carbon, with three species of Citromyces, a genus which he differentiated 

 from Penicillium on rather slight morphological differences, and because 

 of the citric acid fermentation. It has since been recognised that citric 

 acid is one of the commonest products of fermentation by Penicillium. 

 He again used calcium carbonate to fix the acid, and patented a method 

 for commercial production, which, however, was apparently not used to 

 any extent partly because of the slowness of the reaction. 



Aspergillus niger, best regarded as including several closely related 

 species, is one of the commonest moulds and one of the most studied. 

 No mention was made, however, of its ability to form citric acid until 

 1 91 3, when B. Zahorski patented a method of producing the acid from 

 carbohydrates by growing stock cultures of A. niger on increasing con- 

 centrations of citric acid. In 1916 J. N. Currie and C. Thorn made com- 

 parative studies of oxalic acid production in a number of species of Peni- 

 cillium and Aspergillus. The occurrence of a distinct lag in oxalic acid in 

 relation to total acidity in some species of Aspergillus led Currie to regard 

 citric acid as one of the intermediate products of the fermentation. In 



