270 HARRY MARSHALL WARD 



The action of the two components studied separately proved 

 to be not the same as when they worked in concert. This was 

 conspicuously the case with the evolution of carbon dioxide, 

 which proceeded with such violence as to make the research 

 attended with considerable danger. It is known that the action 

 of ferments may be checked by the inhibition of the products 

 formed. Ward pointed out that while the use of these might 

 be advantageous to the bacterium, their consequent removal 

 might be equally so to the yeast. This established the import- 

 ant principle of symbiotic fermentation and gave it a rational 

 explanation. On the morphological side Ward showed that 

 the ginger-beer plant is comparable to a gelatinous lichen, 

 and, having resolved it into its constituents, successfully recon- 

 stituted it. 



The new conception threw a flood of light on many obscure 

 points in fermentation generally, and it is not surprising that 

 Ward's work at once attracted the attention of the brewing 

 industry. It led him to an even more fertile suggestion, that of 

 metabiosis. It was known that the finest wine is sometimes 

 produced from mouldy grapes. He regarded this as a case of 

 one organism preparing the way for another. He returned to 

 the subject in a lecture given at the British Association at Dover 

 in 1899 and pointed out that in the Japanese manufacture of 

 Sake, an Aspergillus prepares the way for the yeast. He 

 also showed that metabiosis played an important part in 

 nitrification. 



Fungi cannot draw their nutriment from solid materials 

 without first profoundly modifying them. They accomplish a 

 large part of their digestion, so to speak, externally to them- 

 selves. This constantly occupied Ward's mind. He insisted 

 on the part played in the process by ferments. The hyphae of 

 Stereum {Phil. Trans. 1898) delignify the walls of the wood 

 elements of Aesculus layer by layer, and then consume the 

 swollen cellulose. He failed, however, to isolate the ferment 

 which does the work. Nor was he more fortunate with the 

 little known fungus Onygena, which grows on horn, hoofs and 

 hair, setting free ammonia as a final product {Phil. Trans. 1899). 

 That there must be some hydrolysis of keratin can hardly be 



