198 BACTERIA, 



example, we have had many cases of both ; the winter 

 previous ('93-94) few of either. This grippe theory of 

 mine I have not been able to demonstrate under the mi- 

 croscope, but simply as a theory it at least has the ad- 

 vantage over the water theory in explaining the wide 

 distribution of the diarrlioeal complaint, which the water 

 theory does not. 



I presume you have all noticed that in the fall, espec- 

 ially during November, there is a decidedly yellow tinge 

 in the city water, and this is accompanied by a somewhat 

 peculiar and fishy odor. This is due to the growth of a 

 very beautiful and graceful diatom called asterionella 

 formosa in the reservoir (not in the river). This would 

 probably grow there whatever the source of the water. 

 Like other plants it has its season of perfect development, 

 and that occurs in November in this climate. It is per- 

 fectly harmless and I know of no way by which we may 

 get rid of it. 



In Sternberg's Bacteriology, the best work on the sub- 

 ject in the English language, which was published in 1893 

 by the present Surgeon General of the U. S. Army, there 

 are described 489 species of bacteria, and of these 158 are 

 pathogenic, i.e., they cause disease either in human beings 

 or in the lower animals. These pathogenic species were 

 undoubtedly ages ago saprophytes but have become para- 

 sitic and remain so, and some of them are among the most 

 fearful scourges of our race. One of them alone, the bacil- 

 lus tuberculosis, destroys one-seventh of the whole human 

 race. It is only recently that the fact was recognized 

 that consumption is an infectious disease, and that it is to 

 a great extent preventable. We are so accustomed to the 

 presence of this terrible scourge among us that we have 

 become indifferent to its presence. Consumptives walk 

 about our streets expectorating millions of these bacteria 

 on the sidewalks, in street cars and in public places 

 generally. The sputum dries up, and the wind blows 



ise 



