PREFACE. 
The present treatise is an introduction to a synopti- 
cal Moss-Flora of Europe and N. America, ready as 
manuscript. 
lt is an essay to define all here belonging genera of 
Bryinee and to dispose themselves in natural families 
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 which 
. 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 
E m in. Tr by the author examined genera and species. 
1 
E^ neglected. A trained bryologist, well-intimate with 
were fertile. 
den "cael 1851; ungelog, was his spe 
Sterile specimens, so often occurring. ought not to — 
the. Organisation of the moss-leaves, ean sometimes. find - e 
new species, as well characterized, as it the kg A 
.. The author was borne his MR Mode. in me Oo 
iality pe = 
