PREFACE. 



The present treatise is an introduction to a synopti- 

 cal Moss-Flora of Europe and N. America, ready as 

 manuscript. 



It is an essay to define all here belonging genera of 

 Bryinese and to dispose themselves in natural famihes 

 with attention also to exotic genera and species. To clear 

 their natural affinity I have often found that the com- 

 mon habit (»habitus») of the plants indicates the place 

 in the system; it is also a »criterium« not to depreciate. 



To state »a priori » the vegetable organs, of vsrhich 

 the characters are to be chosen, does not agree with 

 nature. There are to be found in a certain genus constant 

 characters, which in another are very variable. »Cha- 

 racter non dabit speciem, sed species characterem*. 



Recent bryologists have attached too great an im- 

 portance to the organisation of the peristome. The exo- 

 stome (the outer or the simple peristome) is in many 

 genera, also in individuals, variable. The endostome of 

 the capsule gives indeed good constant characters also 

 in exotic, by the author examined genera and species. 



Sterile specimens, so often occurring, ought not to 

 be neglected. A trained bryologist, well-intimate with 

 the organisation of the moss-leaves, can sometimes find 

 new species, as well characterized, as if the specimens 

 were fertile. 



The author was beginning his bryological studies in 

 Sweden already 1851; bryology was his speciality 1879. 



