BOTANICAL VIEW OF ANTIBIOTICS — JONES 379 



lining their walls. The remainder consists of vacuoles filled with a watery solu- 

 tion of salts. In plant defensive mechanisms the protoplasmic layer may have 

 a detrimental effect on the parasite, and there may also be protective substances 

 present in the aqueous contents of the cell. Among the examples which have 

 been cited to illustrate chemical protection against fungi under natural condi- 

 tions are the presence of protocatechnic acid in the scales of onions resistant to 

 smudge, phenolic substances in wheat varieties resistant to rust and linamarine 

 in varieties of flax showing resistance to Fusarium wilt. Again, it has been 

 recently shown that various phenolic compounds present in apple and pear leaves 

 are toxic to the fungi causing apple and pear scab. Fungicidal compounds have 

 also been isolated from rye, maize and wheat plants. 



One must of course question the advisabilty of man using regularly, 

 as food, plant or animal tissues that carry even a trace of antibiotics. 

 Poultry, beef, and pork may thus be suspect, as farm animals are raised 

 on feed fortified with antibiotics to speed meat production. It is not 

 an easy matter to determine accurately the effects of very slight doses 

 of antibiotics taken into the human alimentary tract over a period of 

 several years. I do, however, believe that the food and drug regula- 

 tions in this country are carefully formulated and realistic from the 

 public health point of view. 



My colleague. Professor Dow V. Baxter, renowned forest patholo- 

 gist, has Ivindly called to my attention that, since 1947, penicillin has 

 been successfully used to control a severe bacterial infection in the 

 giant cactus which graces parts of the Arizona deserts. Diseased cacti 

 attacked by the bacterium Erwinea carneg'ieana were treated by in- 

 jecting penicillin with a hypodermic needle into the lesions. The 

 tissue is largely of a succulent nature, and the antibiotic diffuses 

 through the plant for a considerable distance. 



A recent lead article in the Journal of Forestry (September 1960) 

 states that "a major breakthrough in the control of white pine blister 

 rust caused by the fungus, Cronartium rihicola Fischer, has been 

 accomplished with the antibiotic Actidione. Sprayed on the basal 

 portions of trunks, Actidione is absorbed and translocated upward 

 to kill the causal fungus in blister rust infections on western white 

 pine (Pinus montwola Dough). This work was carried on by joint 

 efforts of the Forest Service and The Upjohn Company, of Kalama- 

 zoo, Michigan." It is pointed out that control of the blister rust has 

 been so phenomenal that "danger exists in becoming too optimistic 

 abut the possibilities of discontinuing a ribes destruction program to 

 prevent new infections." Kibes is a generic name commonly used to 

 indicate both currant and gooseberry bushes, the intermediate host- 

 plants of the white pine blister rust fungus. 



The role of antibiotics in nature is not easy to demonstrate directly 

 because their concentration is so extremely low. To what extent soil 

 microbes, such as Streptomyces and Penicillium, ward off competitors 



