INVISIBLE ASSAILANTS OF HEALTH. 809 



and a bountiful feeder. He must have fluids, semi-fluids, and 

 solids, broths of various meats, peptonized food, the serum of 

 blood, a la Koch, and Pasteur's favorite recipe with the French 

 refinement : Recipe, 100 parts distilled water, 10 parts pure cane 

 sugar, 1 part tartrate of ammonium, and the ash of 1 part of yeast. 

 Among the substantial must be found, boiled white of egg, 

 starch, gelatin, Japan isinglass, and potato— the last, from South 

 as well as North America. 



The appointments of his cuisine, and the extreme care and 

 delicacy of manipulation required, will be shown in the prepara- 

 tion of a broth for the cultivation of a particular species of mi- 

 crobe. First, let it be remembered, all our surroundings are 

 swarming with micro-organisms, a thousand times more numer- 

 ous than the locusts of Egypt, and to exclude them from the 

 kneading-troughs of the micrologist requires all the knowledge 

 of the last quarter of the nineteenth century. A matter of the 

 first importance, then, is that everything connected with the cul- 

 tivation of microbes must be sterilized ; which means that every 

 microbe not wanted for observation must be destroyed ; and no 

 exorcism except by fire or the strongest antiseptics is found 

 available. The preparation of a nutrient material for the culti- 

 vation of selected germs, according to Klein, will illustrate : 



Place in a glass beaker fresh meat and water, equal weights ; 

 boil one hour ; strain through a sterilized filter ; after allowing 

 the bouillon to stand for five hours, boil and filter as before. 

 When cool, place in preserving glasses which have been sterilized 

 by the flame of gas or the hot oven ; then close by sterilized cot- 

 ton, and boil again for over thirty minutes, and cover the mouth 

 of the glass with an inverted beaker, one half filled with sterilized 

 cotton, in order to effectually exclude the germ-laden air. Boil 

 again the next day, and, when cool, place in an incubator for 

 twenty -four hours at a suitable warmth, in order to hatch into life 

 some possible germ of salamander endurance ; and, finally, boil 

 again for more than thirty minutes, in order to destroy this last 

 suspected germ. If everything has been skillfully done, we have 

 now a culture fluid exactly suited to the growth and development 

 of a certain kind of germ only. These numerous steps and pre- 

 cautions for food-making may appear useless and absurd, but a 

 little haste or a false step would undo the work of many days, and 

 only this extraordinary attention to every detail has, after years 

 of investigation, attended with acrimonious discussion among 

 scientists, finally and forever settled the question of " spontaneous 

 generation/' as if in reassertion of the law that every living thing 

 shall bring forth after its kind. 



The method of demonstrating the germ cause of disease is as 

 follows : Using only sterilized test-tubes, forceps, pipettes, cotton, 



