154 PHARMACEUTICAL BACTERIOLOGY 



older lichenologists) and the fungus which make up the lichen individual, 

 nothing more or less than parasitism. Some consider the fungus as the 

 parasite, others the alga. Fiinfstiick, in his grouping of the lichens in 

 Engler and Prantl's Pflanzenfamilien, indeed gives them a place of their 

 own but nevertheless designates them as fungi parasitically associated 

 with algae. This is all the more remarkable since Fiinfstiick very con- 

 cisely sets forth those morphological, physiological and chemical char- 

 acteristics of lichens, which clearly indicate their autonomous nature. 

 He refuses to look upon the relationship of fungus and alga as mutually 

 beneficial, and designates it as a special or peculiar form of parasitism 

 ("Eine besondere Art von Parasitismus ") . It is furthermore a mis- 

 apprehension of the expression "mutualistic symbiosis" to interpret it as 

 meaning that the several symbionts are equally benefited. The term 

 simply implies that the several symbiotic components are benefited 

 (which is frankly admitted by Funfstiick) but that one may receive the 

 greater return favor or benefit. There are some botanists who refuse to 

 recognize in this wonderful biological relationship anything more than 

 ordinary parasitism. Such a deduction is possible only when the compo- 

 nents or symbionts are considered separately and not in their mutual 

 relationship. For example, in like manner it is possible to reach the conclu- 

 sion that the domestic animal is injuriously affected through the influence 

 of man, or that civilized rnan himself is merely a parasitized or degenerate 

 form of the ignorant savage. To speak of the algal (gonidial) symbiont as 

 imprisoned and parasitized is as irrational as to speak of the imprisoned 

 and parasitized horse or cow. It is very true, man uses the milk, the hide, 

 the hair, the teeth, the meat, the bones, the hoof, in fact every part of 

 the animal. It does look like a clear case of the most pronounced one- 

 sided parasitism, but the aspect is changed markedly as soon as we consider 

 both animals, the cow and the man, in their mutual relationship. Had 

 it not been for man, the cow would perhaps not exist at all; as it is, millions 

 of these animals enjoy a life of luxury as compared with the life they would 

 be compelled to lead as independent unparasitized wild animals. Who 

 can then say that the relationship is not mutualistic? By analogy the 

 same argument applies to the alga and fungus in the lichen-group, only 

 here we have a true symbiotic relationship. While it is generally admitted 

 that the lichen components or symbionts may develop and exist in- 

 dependently under artificial conditions, at least up to a certain stage of 

 development, there is no evidence that such is the case in nature. The 

 statement has been made that the algal symbiont may escape from the 

 thallus and vegetate independently on bark, etc., but it lacks proof. 

 Even though that were the case, the fungal symbiont does not exist 

 independently in nature and hence a lichen is an impossibility without 



