20G Dr. A. Carpenter on 



There is sometliing more than smell or something less, as it 

 has not been proved that disease microbes have any smell at all, 

 and, of course, it is only those which cause disease that need be 

 avoided, and the sewer must have a tidal state to enable these 

 germs to find exit at the street openings. This brings me to 

 another point in the case. There are benign microbes as well as 

 malignant organisms. There are microbes which are friends to 

 man, as well as those which are inimical. Take a cubic inch of 

 mould from the Beddington Sewage Farm. It swarms with 

 millions of living creatures, which are hard at work on a warm 

 day preparing the organic matter in the humus by turning 

 its nitrogen into nitrites ready for use by the vegetable world, if 

 it happens that no radicle belonging to a carnivorous plant is at 

 the moment ready to save the necessity for the change. It has 

 been shown by direct experiment that the formation of the 

 nitrites is due to this cause, and that the development of 

 ammonia which takes place under some other circumstances, is 

 also a reaction due to another organism of another kind, the 

 result being acid in the one case, alkaline in another. In the one 

 case putrescence is avoided, a nitrite or other acid being formed; 

 in the other it is hastened, and amrcouia results. Here we have 

 another line. How does this alteration coine about ? The 

 answer is that it comes about very much in the earth or in 

 sewers as it does in the air ; let oxygen abound, especially 

 ozonized oxygen, and nitric acid tends to form. The organisms 

 which cause this tendency grow as vigorously as does the yeast 

 micrococcus in a solution of sugar. When the air is highly 

 charged with electricity, the rain which descends in a thunder- 

 storm contains an appreciable portion of nitric acid. But let the 

 presence of oxygen be diminishing, and compounds of nitrogen 

 form which are alkaline, and putrefaction is then promoted. A 

 set of microbes come into being which are sometimes inimical to 

 humanity ; but here again we see the overruling hand of a 

 Divine Providence, for one of the products of putrefactive 

 agency, namely, sulphuretted hydrogen is completely destructive 

 to those organisms that especially revel in the humours of 

 animal life. This result is shown in the work of the doctor. It 

 is our duty as students to do some dissecting in our student days, 

 and we may be requested to do so at any time by the coroner. It 

 sometimes happens that the operator wounds himself. I have 

 experienced this while making post-mortem examinations upon 

 those who have only been dead for forty-eight hours, more or less. 

 This class of wound is always very serious, for disease germs 

 may be transplanted ; but a wound inflicted at the end of a dis- 

 section, when putrefaction is established, perhaps six or eight 

 weeks after the death of the subject, has very little danger in it, 

 for tiic disease-producing microbes, if they had been present, 



