22 



THE ACTIXOMYCETES, Vol. I 



Figure 15. Growth of actinomycetes in natural substrates, as shown by contact sliile method. Some 

 definitely belong to the Microtnonospora and others to the Streptomyces types. 



the material to be examined. A clean cover 

 slide is placed in close contact \vith the fresh 

 soil, manure, or compost material. The slide 

 is allowed to remain undisturbed for 1 to 3 

 weeks, then removed, and cleaned on one 

 side. It is dried, fixed over a flame, carefully 

 washed to remo\^e coarse particles of soil or 



organic residues, and stained with a suitable 

 dye, such as phenol-erythrosin. 



The contact slide method offers certain 

 ad\'antages over the direct examination of 

 soil or other material and over the direct 

 staining of such material. It permits the 

 development, on (he slide, of organisms pres- 



