398 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1950 



It has been assumed in the past that the presence of the enzyme 

 lichenase in the stomach contents of the ox and pig probably enables 

 these animals to convert lichenin into the more digestible sugars. The 

 action of snail lichenase on lichenin in vitro has been found to pro- 

 duce cellubiose and lichosan, an anhydride of glucose similar to cello- 

 san, a product of cellulose. Messerle (13) states that the livers of 

 snails contain much lichenase, which converts cellulose to sugar. 

 Jewell and Lewis (13) had found this to be true of many invertebrates, 

 suggesting that the ability to hydrolyze lichenin may be characteristic 

 of invertebrates only. 



Swartz (13) questions the value of algae and lichens as sources of 

 energy in nutrition. Oshima suggests that they may be valuable for 

 their inorganic salts, while Prausnitz (13) calls them "faeces-forming 

 foods" in that they stimulate intestinal activities. Most of Swartz's 

 studies were on the algal components, yet she was able to draw certain 

 conclusions concerning those chemical substances which are common 

 to both components. They were : 



a. Nutritive studies of lichens would indicate that as energy- 

 producers their value is not appreciable. Yet the fact remains that 

 certain animals do feed upon them and thus sustain themselves in 

 regions where energy and high body heat are prerequisites of life. 

 The assumption follows that our understanding of the value of lichens 

 as fodder is still incomplete, though ruminants are apparently more 

 effective users of hemicellulose than other animals. 



h. Aerobic and anaerobic bacteria, not enzymes, are responsible 

 for conversion of hemicelluloses into sugars. The amount available to 

 the animal system is extremely diverse, depending on the animal and 

 the lichen species. 



Vitamin studies. — Blix and Kydin (13) found that Gladonia rangi- 

 ferina contains some ergosterol, more than most lichens, but the con- 

 tent is low in comparison to that in yeasts and molds. This same 

 species collected in Uppsala in August and September showed only 

 traces of vitamin D. Bustinza and Lopez report (3a) that they 

 "obtained a fraction very rich in ergosterol" from Evernia furfuracea 

 collected in Spain. 



Experiments with rats in Alaska, using lichens arbitrarily divided 

 into short- and tall-growth forms, indicated that the animals would 

 not tolerate the latter group (Cetrariae, Cladoniae) at levels greater 

 than 10 percent in pure diets. Short-growth types ( Alectoriae, Stereo- 

 caula, etc.) appeared more palatable. Vitamin- A and -D response was 

 obtained from tall-growth types; vitamin-B complex was absent in 

 both groups. Bourne and Allen (13), using acetic acid-silver nitrate 

 reagent for vitamin-C, obtained a positive test. 



