Economic Importance of Plants 251 



isms, noted the presence of a contaminating mold colony (Penicillium 

 notatum) (Fig. 73) and noted that the Staphylococcus organisms sur- 

 rounding the mold colony were undergoing lysis (destruction). Thus 

 began the steps to obtain, cultivate, and purify the most remarkable 

 chemical therapeutic agent for the treatment of certain types of bacterial 

 infections. The progress made in the production and use of penicillin 

 has been so great and fast that one can only guess of the possibilities of 

 the future. Some of the characteristics of penicillin are as follows: it is 

 a light brown powder (as now used) ; appears to be virtually nontoxic 

 in doses required for therapeutic purposes; is highly selective in its 

 action, being capable of destroying certain bacteria without injury to 

 body cells; is highly soluble in water or saline solution; is stable to light 

 but is affected by heat; when administered, it is rapidly excreted in the 

 urine; is highly successful in the treatment of many diseases which here- 

 tofore have been difficult to treat. 



Fig. 73. — Two common fungi, (A) Penicillium sp. and (B) Aspergillus sp., 

 which produce penicillin and other antibiotic substances used in the treatment of 

 numerous diseases. 



In spite of the wide and successful use of penicillin, scientific workers 

 are still attempting to discover other antibiotic substances which may be 

 equally satisfactory. In fact, dozens of antibiotic substances are known 

 to be produced by molds, bacteria, actinomyces, a certain unicellular 

 Alga (Chlorella sp.), certain weeds and flowering plants, soybean flour, 

 common garlic, etc. All of them are being tested, and some show great 

 promise. 



