658 Transactions of the American Institute. 



a dirty green color, and of a most disagreeable smell, and depositing 

 considerable sediment, consisting principally of sand and humified 

 organic residue. A great variety of animal and vegetable organisms 

 were not found. 



In all cases they discovered : 



1. Infusoria in abundance, among which predominated amoeba 

 dim uens, monas lens, cersomo-monas, paramerium aurelia, stylony- 

 shia mytilus, and on the surface vorticellen. 



2. Algae containing chlorophyl of a green color were seldom 

 found in the fresh sewage, although occasional threads of spirogyra 

 and ulothrix were seen. Oscillarien were plentiful and in active 

 motion. 



3. None of the well-known species of fungus were found in the 

 fresh sewage, although threads of leptothrix and torula cerebisiaB 

 were always to be seen. 



4. The batrachian order of animals, and they were found to be 

 exceedingly numerous in the sewage. Bacterien were in abundance, 

 and particularly the miero and mona bacterien of Hoffmann, which 

 were in active motion. Monas bacterien of Hoffmann, single cell 

 organisms, were found in great activity. Spirillen, lineal formed 

 bodies, having a lively serpentine motion, were also found. 



Besides the above, there was found on the surface of the sewage 

 numbers of very small cells, singly and in groups. 



An examination of the air of the sewers was done by allowing the 

 air near the surface of the fluid to pass for two hours through a filter 

 of gun-cotton. A part of this was afterwards dissolved in ether and 

 examined under the microscope, when traces of fungus and monas 

 bacterien were found, the last of which 'was very numerous. 



A part of this gun-cotton that had been used as a filter was placed 

 in fresh bailed urine and sealed up tightly. 



In another portion of the same urine ordinary gun-cotton was 

 placed, and both vessels were allowed to stand fourteen days, when 

 both tests were found to contain bacterien in active motion. 



Although the surface of the fluid in which the ordinary gun cotton 

 was placed remained comparatively clear, the surface of that in which 

 the gun-cotton, used as a filter, was placed was covered with a thick 

 coating of mucor racemosus. 



These examinations throw some light upon the organic changes 

 that take place in the sewage, and although at present the results 

 obtained are very unsatisfactory, still I believe that such investiga- 



