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App.il 14th. 

 The following paper was read by the President : — 



ON GEEMS. 



There is perhaps no topic which has excited greater scientifie 

 interest and provoked warmer discussions than the so-called Germ 

 Theory, or the influence of micro-organisms in the economy of 

 nature and the causation of disease. The investigation of the 

 infinitely small has always exercised a wonderful fascination over 

 the minds of scientists, who ever desire to trace back step by step 

 all life to a first cause — a primeval atom — and to follow all the 

 tortuous windings of disease until the actual origin is found, the 

 first germ, the infinitesimal molecule. Bacteriology, or the study 

 of these minute organisms, is, however, too vast a subject to be 

 adequately treated in the short space allotted to me. I marely 

 propose this evening to touch upon a few of the more interesting 

 points connected with this science, especially as illustrated by the 

 discoveries of that great chemist and scientist, M. Pasteur. There 

 is no other living man who has done more to benefit society by 

 his patient and laborious investigations into the origin of disease, 

 which, thanks to his indefatigable zeal, may be said to have 

 revolutionised the whole science of medicine and surgery. 



The manner in which M. Pasteur's labours were directed 

 towards this special subject of bacteriology is not perhaps generally 

 known, and it is somewhat interesting as illustrative of the homely 

 proverb that " small beginnings make great endings." 



Some forty years ago the minds of many eminent chemists were 

 greatly exercised by the incomprehensible behaviour of the so- 

 called 'isomeric bodies,' viz., compounds which, though possessing 

 an identical composition, appear, to judge by their chemical action 

 and optical properties to be totally different substances. The 

 great Swedish chemist Barzehus, and later on Biot, vainly 

 endeavoured to solve the problem why two acids which were 

 constituted alike had altogether dissimilar properties. I refer to 

 the ordinary tartaric acid of wine-lees which possesses the power 

 of deviating the plane of polarised light to the right, and a rare 

 acid found occasionally in the tartar deposited from wine made in 

 the Vosges district, and which is optically inactive. This per- 

 plexing question attracted the attention of the then unknown 

 Pasteur, and for seven years this indefatigable chemist proceeded 

 with his experiments, which were ultimately rewarded with 

 success. He discovered that the rare acid itself was made up of 

 two compounds which were identical in composition but differed 



