402 ANTSrUAL REPORT SMITHSONIAN INSTITUTION, 1950 



Raistrick (15) introduces new findings, however, remarking that the 

 isolation of two lichen acids, parietin and physcion, from the lower 

 fungi is an ". . . observation ... of some biological interest since 

 ... (it) gives strong evidence for the view that the so-called lichen 

 acids owe their origin to the fungal half of the fungus-alga symbiont. 

 . . . The presence of chlorine containing metabolic products (of 

 the Lower Fungi) emphasizes the close metabolic relationship be- 

 tween moulds and lichens, since two of the very few organic chlorine- 

 containing substances occurring in nature have been isolated from 

 lichens, i. e., gangaleoidin and diploicin." Research on lichen acids 

 began with the Germans — Zopf, Hesse, Fischer, and others — but 

 received most attention from the work and simplified methods of 

 extraction of Asahina and his Japanese colleagues. These studies are 

 being conducted today by Rao, Sastry, Seshadri, and Subrumanian, 

 of Andhra and Delhi Universities, India; by Robert L. Frank and 

 his students at the University of Illinois; by F. Bustinza and C. 

 Lopez, Madrid, Spain ; by the workers at University Ck)llege, Dublin, 

 under the late Prof. T. Nolan — Breaden, Davidson, Hardiman, Jones, 

 Keane and Murphy — and V. C. Barry, all of whom are contributing 

 detailed information on the chemical constituents of the lichens 

 in their respective areas. The research of these workers is basic to 

 the recent experimental aspects of lichenology. In view of present- 

 day research, this information has passed from the sphere of academic 

 interest and begins to assume real value in practical application as 

 well as presenting a more complete understanding of the biology of 

 this group of plants. 



Since the discovery of the chemotherapeutic effects of penicillin, 

 the phenomenon of antibiosis has attracted widespread attention and 

 stimulated the investigation of other plant groups. Some investiga- 

 tors (2), studying the antibiotic activity of lichens, proceeded with 

 their studies because : "In view of the reported antibacterial activity of 

 the green alga Chlorella and the many antagonistic substances now 

 known to be produced by numerous kinds of fungi, the lichens seemed 

 to offer favorable material for antibiotic investigations inasmuch as the 

 bodies of these plats are comprised of mixtures of algae and fungi." 

 Using the cylinder plate procedure, they analyzed the antibacterial 

 activity of extracts from 42 species of lichens, later extending the work 

 to 100, of which 27 species were found to be active against Staphyloco- 

 cus aureus and BacUlus suhtilis, while 2 species inhibited the growth of 

 Proteus vulgaris and 2 species showed slight inhibition against Alcali- 

 genes fecalis; none of the lichen extracts used in the test showed antag- 

 onism against Escherichia coli. That more than one antibiotic com- 

 pound may exist in lichens is suggested by the fact that both S. aureus 

 and B. suhtilis are inhibited by extracts from Cladonia grayi^ Parmelia 

 physodes and other lichens, while substances obtained from some spe- 



