2 9 



ous period maintained that lichens formed a distinct class of plants. 

 But Tuckerman and Reinke had entirely different conceptions as to 

 the nature of lichens. The former did not believe in their dual nature 

 and, therefore, could not form any true idea as to the relation they 

 bear to other groups of plants, the fungi and algae in particular. 

 For that reason we are justified in stating that Reinke was the first 

 to indicate the true position of lichens in the vegetable kingdom. 



Lindau (53) is opposed to Reinke's views and strenuously up- 

 holds the theory of Schwendener. As has already been indicated, 

 the future must decide which theory will prevail. 



Reinke also pointed out the polyphyletic origin of lichens (75, 

 III, IV). The various groups (usually generic) of lichens are 

 derived from different fungal ancestors. Usually several fungal an- 

 cestors have become associated with the same algal type, or the same 

 fungal type may have become adapted to different algal types. 

 Reinke has proposed a system based upon this polyphyletic relation- 

 ship, which, when more perfected, will form the first approximately 

 natural system of classification for lichens. As this author states, to 

 study the exact phylogenetic relation of lichens to fungi and algae, 

 is one of the important works of the future. 



Fimfstiick (32) has investigated the fatty secretions found within 

 crustaceous rock lichens. His conclusions are briefly summarized 



/ 



as follows : Calcivorous crustaceous lichens vary greatly as to the 

 depth to which they penetrate the substratum ; the endolithic forms 

 have a deficient algal layer as compared with the epilithic forms ; 

 the fatty deposition increases with the increase of the gonidial 

 layer, but has no genetic relation to it ; the fatty substance is de- 

 posited in the hyphae lying within the substratum ; fat is deposited 

 only in lichens growing upon a substratum bearing carbonates ; the 

 formation of the fatty substance is very likely initiated by the de- 

 composition of the carbonates. 



Lindau (54) has also issued the first of a series of communications 

 on the morphology and physiology of lichens. Part i treats of the 

 growth and mode of adhesion of crustaceous bark lichens. He con- 

 cludes fhat the hyphae never penetrate the intact cells of the sub- 

 stratum. He has also considered the question whether lichens 

 have or have not an injurious effect upon trees (54)- He comes to 

 the conclusion that they have no injurious effect upon trees growing 

 under normal conditions. Only when the trees are growing in poor 



