152 01. AF GALL0K 



away at the base; (3) procumbent, dorsi ventral, hapteron-producing 

 podetia, dying away at the base behind; (4) procumbent, dorsiventral, 

 hapteron-free podetia, dying away at the base behind. 



Type 1 is found only in the hypothallus-wanderers, and in the 

 majority of these. 



Type 2 is found in some of the hypothallus-wanderers, and in 

 all the podetium-wanderers. As a rule, we may take for granted 

 that podetia of type 1, when they become old, ultimately pass over 

 to type 2 for a short time, before they die away entirely. But even 

 if the boundary line between the two types is thereby made very 

 uncertain, it is advisable to maintain both of them, as there are 

 undoubtedly species which never die away below or, at any rate, 

 very rarely do so (e. g. Stereocaulon condensatnm, Cladonia papillaria, 

 (]. pyxidata, C. pityrea and possibly others). 



Type 3 like type 4 is commonest in the podetium-wanderers, 

 in which the edge of the tuft usually grows in circumference by 

 the marginal podetia lying down and creeping over the surface of 

 the ground, and like runners spreading out on the substratum. By 

 this the podetia often become somewhat dorsiventral and, in addi- 

 tion, send in some cases haptera into the ground (the majority of 

 the podetium-wandering Cladonias); in other cases nothing like this 

 happens (Stereocaulon, Dufourea). 



Consequently, in the same tuft and in the same species more 

 than one type of podetium may be found, so that types 1 and 2 

 are united, in that the old podetia may belong to type 2, and the 

 young, on the other hand, to type 1 ; but, as already mentioned, 

 in some species type 1 is the dominant one. 



Types 2 and 3 are, as a rule, united in the same species and 

 in the same tuft, in that type 3 forms the runners of the tuft, and 

 type 2 the old erect shoots in the middle of the tuft. 



In the same way, types 2 and 4 are as a rule united in the 

 same tuft. 



It is evident, that all species which have on the whole erect, 

 permanent podetia, are less adapted to grow on the earth, because 

 they are so dependent on the substratum for their attachment, and 

 are therefore easily overgrown and crowded out by other species. 

 Their apical growth also is very limited, which in addition reduces 

 their capacity for competition. 



Podelium-wanderers, on the other hand, are excellent compe- 

 titors. With regard to these I shall add some further notes about 



