XVm BY J. THOMSON, M.n. 



inevitable that the different kinds of bacteria will produce 

 different results as to flavour and grade in the fermenting 

 processes." 



The effects of other friendly bacteria are seen in the 

 *' retting " of the linen and the jute trades ; the preparation of 

 indigo and the curing of opium. 



But another, a more recent, and, if successful, perhaps the 

 most important of all the friendly aids which man receives from 

 lowly life, is the bacterial treatment of sewage. '•''■•^' The disposal 

 of the sewage of cities has been one of the conundrums the 

 sanitary engineer or expert has had to wrestle with since cities 

 first began. It is unnecessary to enumerate the various schemes, 

 more or less successful which have been adopted for all the 

 various conditions of differently situated towns. In most or all 

 of these there has been some one weak or defective spot (even if 

 only an economic one) apparent to and claiming the attention of 

 the authorities, and they, calling in the aid of the scientist 

 have been informed of " the utilisation of bacteria in the treat- 

 ment of sewage," as proposed by Scott Moncrieft" in 1892. The 

 scheme, in fair detail, but somewhat too lengthy to quote in full 

 to-night, appears in an able paper on " Sewerage and Health," 

 read by Dr. Mailler Kendall, JNledical Adviser to the Sydney 

 lioard of Waterworks, at the Brisbane Session of the Inter- 

 colonial Medical Congress of Australasia, in September, 1899. 



And this bacterial treatment of sewage or as it is referred to as 

 " simply allowing Nature to fulfil her function by means of 

 bacteria," is also described in " Bacteria," one of the volumes of 

 The Progressive Science Series, 1899, and the works at Exeter are 

 explained and plans shown. 



If the proinise of the present be supported by the experience 

 of the future, Science, for the problem has been carefully worked 

 out on Chemico-Vital lines, will have scored one of its very 

 biggest successes. 



I have said nothing of the numbers in all the classes of 

 , bacterial varieties — it is impossible — they are " As the sand 

 which is by the sea shore, innumerable ; " and it is almost 

 equally impossible to refer to tli u- r.ipi lity of multiplication, 

 but as I quoted Engel on yeast, 1 may be excused for mentioning 

 Cobn on bacteria. 



He calculated that a single germ could produce by simple 

 fission two of its kind in one hour, in the second hour these 

 would be multiplied to four ; and in three days they would, if 

 their surroundings were ideally favourable, form a mass which 



