180 THE AMERICAN MONTHLY [August, 



human system resembling those of cholera infantum, and Dr. V. C. 

 Vaughn, who discovered this poison, suggests that this may be the 

 chemical irritant producing this disease. And what is true of cholera 

 infantum is perhaps true of typhoid fever, and many other diseases, 

 but not at the same stage of life. 



While some persons are easily infected, it is also true that many 

 seem insusceptible to the germs of disease, and, although much exposed, 

 they pass through long lives unscathed. " This insusceptibility varies 

 indefinitely, or it may exist at one period of life and' then unfortunately 

 be lost, or a new and greater susceptibility be acquired at other times. 

 The conditions that determine susceptibility or insusceptibility cannot 

 be defined in the present state of knowledge. There are certain pe- 

 riods of life when the human body cannot be infected — infantile period, 

 old age. At the extremes of life the typhoid germs can make no im- 

 pression, because of the absence of necessary conditions. The essen- 

 tial lesions to constitute any one case of typhoid, are thickening, ul- 

 ceration of the glands situated in the lowest part of the small intestines 

 (Peyer's patches), and similar changes in what are known as the ' soli- 

 tary glands.' At the earliest period of life these glands are not suffi- 

 ciently developed, and in old age they are too much wasted, to furnish 

 a nidus for the reception and growth of the parasite. It is not possi- 

 ble to indicate the precise period when these glands acquire full devel- 

 opment, or become too much wasted to take on the typhoid infec- 

 tion.* " 



Bacteriology is the newest of the sciences, and yet it has become one 

 of the most interesting fields for the truly scientific investigator. No 

 chemist and no pathologist can afford to remain ignorant of what has 

 already been learned of the workings of the microscopic world around 

 us, for many of the most interesting chemical changes are produced by 

 bacteria, and many of the most dangerous maladies have been traced 

 to them. 



o 



Japanese Filter Paper. — The Japanese filter paper so commonly 

 used for cleaning objectives, etc., appears on microscopical examina- 

 tion to consist of very thin-walled bast fibers. By comparison with 

 other papers, Dr. Uloth was able to identify it as derived from the 

 shrub Wickstroemia canescens, which grows in the mountains of Mid- 

 dle and South Japan. The plant belongs to the same botanical family 

 as the Mezereons of Europe. The paper goes under the name 

 " Usego." — Pharttiaceutical Record^ March 26^ i8gi. 



Introduction to the Study of Mosses. — Popular Science News 

 for March, 1891, has a posthumous paper from the pen of the late Prof. 

 Leo Lesquereux, entitled the General Character of Mosses. It was 

 originally prepared for the Manual of the Mosses of North America, 

 from which it was omitted to save expense. We regret the omission, 

 and call attention to this publication, because thus far little, if anything, 

 of the kind has ever been published in America. 



? Report of Iowa State Board of Health, 1889. 



