SAPROPHYTES 387 



above the substratum, and that they are light and powdery, 

 do you wonder that the spores of mold are abundant every- 

 where? Do you see that the molds are highly fitted to com- 

 pete with us for possession of our food? 



In this way, study all the different kinds of molds that you 

 have collected. Your instructor will be able to tell you the 

 names of several of the different kinds of mold that you study 

 and you will be able to identify some of them by comparing 

 them, as you study them, with the different figures in the text. 



FIG. 266. Penicillium. FIG. 267. Antenaria. 



Exercise 87. Identifying Molds on Different Materials 



After you have learned to identify several different kinds of molds, 

 select one or two of them and see how many different kinds of material 

 you can find them growing on. If you select the common green mold, 

 PENICILLIUM, for example, you should find it growing on a great 

 variety of different substances (Fig. 266). Cheese, cured meats, 

 stale bread, old clothing, old shoes, indeed, almost any kind of plant 

 or animal matter may afford food for this mold. Note that the gen- 

 eral appearance of a given mold varies considerably as it grows in 

 different situations. 



439. Conditions which Favor Mold Growth. If we are to 



be successful in warding off the attacks which molds make on 

 the things which we wish to preserve, we must understand the 

 conditions which are favorable for mold growth. Everyone 

 is familiar with the fact that molds do not grow on materials 

 which are quite dry. One of the earliest methods which man 

 ever devised for the preservation of food is that of drying it. 

 A certain amount of moisture must be present before molds can 

 grow at all and a considerable amount is necessary for a lux- 



