322 THE MICROSCOPIST. 



reveal valuable facts. Solid fragments of carbon or silex, 

 etc.. starch grains, filaments of cotton, flax, wool, silk, 

 etc., spores of fungi, animal and vegetable debris, etc., all 

 require considerable familiarity with microscopic objects 

 in general, without which no one should undertake such 

 investigations. 



Minute living particles of bioplasm, either ordinary pus 

 or what Dr. Beale calls "disease germs," should be dili- 

 gently sought for under high objectives. 



Pollen-grains are often found in the air. In Schuylkill 

 County, Pa., in the summer of 1858, after a rain-shower, 

 a yellow scum of pollen covered all the pools, and was 

 traced over a tract of fifty by twelve miles. Showers of 

 "flesh" or "blood" have been described in newspapers, 

 which were probably varieties of Nostoc (page 151), or pig- 

 ment bacteria (page 326). 



The subject of bacteria germs in the air has lately ac- 

 quired great interest from the success of the antiseptic 

 method now generally pursued in large surgical opera- 

 tions, and first introduced by Mr. Lister. This will be 

 considered under the head of disease germs. 



The examination of the breath of men or animals may 

 be made by means of glycerin on glass slides, or by breath- 

 ing through a glass tube containing cotton-wool, which 

 may afterwards be washed with dilute glycerin. Epithe- 

 lial cells, oil-globules, fragments of food, soot, fungi, etc., 

 may thus be detected, or the expired air may be tested 

 for ammonia with hydrochloric acid. 



II. EXAMINATION OF SOIL AND WATER. 



The soil may be examined both chemically and micro- 

 scopically according to the methods given on former pages 

 of this work. The importance of such examination will 

 be plain in many cases of local diseases. It is stated that 

 the mortality caused by murderous epidemics in England 



