NOTES. 



H3 



tests show that it has lost nearly all its power 

 of pollution. Thus, the number of 198,000 

 bacteria per cubic centimetre found by Praus- 

 nitz at the mouth of the Munich sewer was 

 reduced at Ismaning to 15,231, and at Frei- 

 sing to 3,602. A similar result was obtained 

 by Frankel with the water of the Spree at 

 and below Berlin. The mere number of 

 bacteria found has, however, no sanitary sig- 

 nificance, since these particular microbes are 

 mostly harmless, and in fact destroy the patho- 

 genic microbes in the struggle for existence. 

 The purifying action of rivers is ascribed by 

 von Pettenkofer to the oxygen dissolved in 

 the water in a free state or separated from 

 organisms. In the latter respect the green 

 algae and even non-chlorophyllic plants come 

 prominently into consideration. This vegeta- 

 tion should be preserved ; but it may be de- 

 stroyed by a too great concentration of the 

 water to be purified ; and to prevent this, in- 

 dustrial waste waters which destroy vegeta- 

 tion must be kept out till they have been 

 purified. 



Bacteriological Processes against Dis- 

 ease. — According to a summary in the Satur- 

 day Review, attempts by bacteriological pro- 

 cesses to remove from the human system the 

 germs of infectious disease have been made 

 by six different methods. The first is by 

 Pasteur's preventive inoculation, in which a 

 minute quantity of an attenuated culture of 

 the virus is administered to produce a light 

 attack of the disease. The second is M. 

 Pasteur's method in rabies, in which a miti- 

 gated virus is injected into a person already 

 attacked with the disease, to overtake it. 

 The third is the employment of the virus of 

 a comparatively mild disease to protect 

 against a more severe one, as in vaccination 

 for smallpox. Next in order is the destruc- 

 tion of the disease-producing bacteria by the 

 administration of antiseptics or bactericides. 

 A fifth method is the re-enforcement of natural 

 means possessed by our systems for combat- 

 ing disease germs : by re-enforcing the leuco- 

 cytes or white blood-corpuscles, which de- 

 stroy bacteria, by means of the injection of 

 the blood of animals insusceptible to the 

 disease ; by raising or lowering the tempera- 

 ture of the body of the patient; by alter- 

 ations of diet, climate, or surroundings ; or 

 by injection of phagocyte invigorators. The 



sixth method is by the injection of the " tox- 

 albumens " formed by the bacteria growing 

 in artificial cultures, as is done in Koch's 

 method for tuberculosis. That these methods 

 have not proved entirely satisfactory, and 

 bacteriological treatment is now apparent- 

 ly at a standstill, is not due, it is thought, 

 to any innate defect in the system, but to 

 some technical detail. " When the ingenuity 

 of man has arrived at the point of being able 

 to prove absolutely that organisms, complete- 

 ly invisible to all but the highest magnifying 

 powers attainable, cause each its particular 

 infectious disease ; when these tiny things 

 may be made to grow like plants in a garden, 

 separately and in order ; when we can keep 

 rows of tubes each with its deadly contents 

 on our laboratory shelves, or in our incuba- 

 tors, like druggists' bottles of inert powders 

 or crystals — surely we shall not stop at this 

 stage in our control over this ' world of the 

 infinitely little.' " 



NOTES. 



A clarification of muddy liquids and 

 partial separation of micro-organisms is 

 effected by M. R. Leze by subjecting the 

 liquid to a rapid rotation. Thus, cider, in 

 turbid fermentation, after being whirled in 

 a turbine wheel, came out clear ; and while 

 specimens kept in bottles at 86° soon gen- 

 erated bacteria, the yeast and alcoholic fer- 

 mentation had all disappeared. This method 

 may be found useful in bacteriological inves- 

 tigation ; and in industrial operations, for rid- 

 ding impure and unhealthy waters of most 

 of the organisms contained in them. 



Chemical analysis has been applied by 

 M. Berthelot to the solution of a problem in 

 archaeology. Taking a piece of copper found 

 by M. de Sarzec in his explorations of the 

 ruins in Mesopotamia, which was obtained 

 from one of the most ancient sites, he made 

 an exact determination of its composition. 

 It contained no tin or zinc, and only slight 

 traces of lead and arsenic. It had been oxi- 

 dized throughout, and presented itself as a 

 suboxide or a mixture of protoxide and me- 

 tallic copper. Hence, while the question 

 can not yet be considered decided, the speci- 

 men is a contribution of evidence in favor of 

 the existence of an age of copper. 



The physicians of Massachusetts have in 

 recent years noticed a development of ma- 

 larial disease in Cambridge and the vicinity 

 of Boston and in other towns of the State. 

 The origin of the cases in Cambridge seems, 

 from the investigations thus far made, to be 



