158 NATURAL SCIENCE. September. 



destroys or changes. Now, these changes are destructive to the life 

 of minute organisms, such as the bacteria in sewage, and the germs 

 of many, perhaps all, zymotic diseases, such as typhus and anthrax. 

 These are the conclusions to be gathered from the recent work of 

 Professor Marshall Ward, Dr. Arthur Richardson, and Dr. E. 

 Frankland. 



We must have sunlight. In our rapidly-growing cities its 

 admission is a necessity for the commonweal, its exclusion a crime. 

 But hitherto the conditions of city life, in England at least, have 

 tended more and more towards the exclusion of sunlight. The smoke 

 that goes up, not only from our factories but from every private house, 

 that stretches over London like a veil even on the clearest summer 

 Sunday, this not merely acts directly as a screen against the sun, but 

 condenses around its particles the vapour of the atmosphere, forming 

 mists, pea-soup fogs, and rain-clouds, all which shut off from us just 

 those violet rays that we need for the destruction of the rapidly- 

 increasing bacteria. Professor Ramsay, speaking in the smoke- 

 vomiting city of the north, urged the same remedies as have been 

 urged by all who have thought on this subject ; first, more stringent 

 enforcement of the Smoky Chimneys Act, and of municipal bye-laws 

 against smoke ; secondly, the adoption of smokeless fuel, such as coke 

 or coal-gas. 



Professor Ramsay's valuable and thoroughly interesting address 

 should be studied by all town and county councillors, and we should 

 like to see it reprinted and placed in the hands of all householders 

 and especially housewives. The gas companies might undertake its 

 distribution along with the quarter's notice. 



The Disposal of Sewage. 



Professor G. V. Poore, at a lecture delivered at the Royal 

 Institution on April 24, 1896, discussed the disposal of organic waste 

 matter. He began by explaining in detail the general course of the 

 circulation of organic matter, and the part played by fungi and 

 bacteria in the cycles of change. Quoting from Mr. Megnin, the 

 French entomologist, he gave an account of the successive sets of 

 insects that appear in gradually decomposing animal matter ; while on 

 the authority of Mr. George Murray, he described the varieties of 

 moulds that assist the decomposition of the dung of different kinds of 

 animals. These interesting facts were the prolegomena to his first 

 proposition, the proposition that the superficial layer of humus, full 

 of bacteria, is the great cleansing filter of the world. Organic matter 

 that is mixed in due proportion with this humus, if it be not flooded 

 by water, is rapidly decomposed into a condition which makes it the 

 best possible manure for crops. Just as a valuable soil is gradually 

 formed on barren rocks by the growth and decay of various forms of 

 animal and plant life, so, according to Professor Poore, a due use of the 



