596 TRANSACTIONS OF SUB-SECTION 



task afterwards by a prominent advocate of the new school for raising a side 

 issue. Breeding was a purely empirical affair. Common-sense and selection 

 comprised the whole business, and physiology flew at higher game. I am, 

 nevertheless, happy now to reflect that of the work which is making the Cam- 

 bridge School of Agriculture a force for progress in the agricultural world the 

 remarkable researches and results of my late colleague, Professor Biffen, based 

 as they have been on modern discoveries in the pure sciences of breeding, 

 occupy a high and greatly honoured place. 



In conclusion I would sound once more the note with which I began. If we 

 are to progress fast there must be no separation made between pure and applied 

 science. The practical man with his wide knowledge of specific natural facts, 

 and the scientific student ever seeking to find the hard general truths which the 

 diversity of Nature hides— truths out of which any lasting structure of progress 

 must be built — have everything to gain from free interchange of experience and 

 ideas. To ensure this community of purpose those who are engaged in scientific 

 work should continually strive to make their aims and methods known at large, 

 neither exaggerating their confidence nor concealing their misgivings, 



' Till the world is wrought 

 To sympathy with hopes and fears it heeded not.' 



The following Papers were then read :— 

 1. Cider-Sickness. By B. T. P. Barker, M.A., and V. Florian Hillier. 



Cider-sickness is a disorder of common occurrence which generally makes its 

 appearance in ciders in the early part of the summer. The first symptoms of the 

 attack are a characteristic frothing of the liquor and a sudden and violent evolu- 

 tion of gas. The pleasant fruity character of the cider disappears and a dis- 

 agreeable peculiar odour and taste are produced. After a short time the cider 

 generally becomes turbid and suffers some loss of colour. In some cases the 

 turbidity increases until the liquor attains a thick milky condition, while in other 

 instances the cider itself remains comparatively clear but a copious deposit is 

 precipitated. The turbidity is due partly to bacteria mixed with a few yeast 

 cells und tnrula?, but mainly to the formation of a substance which is thrown out 

 of solution in the form of aggregations of minute droplets or granules which when 

 examined microscopically may easily be mistaken for groups of small cocci. Ihe 

 nature of the substance has not yet been fully investigated, but it is possibly 

 a derivative of the colouring matters of the cider. It is partially dissolved on 

 heating the cider and is, when freshly precipitated, soluble in alcohol. Occasion- 

 ally the deposition of this substance is absent in cases of sickness. 



'The «-as evolved during sickness consists mainly of carbon dioxide, and a small 

 percentage of hydrogen is also produced. The specific gravity of the cider falls 

 rapidly during sickness, owing to the destruction of the sugar, and the percentage 

 of alcohol is increased. The acidity also rises slightly. Under conditions 

 favourable to the disorder the fermentation may continue until the sugar almost 

 entirely disappears; but occasionally, for what reason it is not at present clear, 

 it may suddenly cease, leaving a considerable quantity of sugar untouched. 

 Cider after sickness is prone to rapid acetification. Ciders most liable to sickness 

 are those containing relatively large amounts of unfermented sugar, and are 

 generally those of the best quality. Consequently the loss to the makers is very 

 serious "and probably amounts to several thousands of pounds per annum in the 

 West of England alone. Other conditions favouring sickness are a naturally slow 

 rate of fermentation of the cider, a low degree of acidity, and a high temperature. 

 Contrary to the generally accepted idea the presence of a large amount of tannin 

 in the cider does not appear to offer much check to the disorder. 



Perry is also liable to the same trouble. 



An examination of the flora of sick ciders has led to the isolation of a 

 bacterium which can produce all the symptoms of sickness in sterilised ciders and 

 perry infected with pure cultures of it. The characters of the organism have 

 been studied in detail. It is motile and facultatively anaerobic Its optimum 

 temperature of growth is about 30° C. No growth has been observed above 40 C., 



